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http://rosettacode.org/wiki/Brownian_tree
Brownian tree
Brownian tree You are encouraged to solve this task according to the task description, using any language you may know. Task Generate and draw a   Brownian Tree. A Brownian Tree is generated as a result of an initial seed, followed by the interaction of two processes. The initial "seed" is placed somewhere within the field. Where is not particularly important; it could be randomized, or it could be a fixed point. Particles are injected into the field, and are individually given a (typically random) motion pattern. When a particle collides with the seed or tree, its position is fixed, and it's considered to be part of the tree. Because of the lax rules governing the random nature of the particle's placement and motion, no two resulting trees are really expected to be the same, or even necessarily have the same general shape.
#Nim
Nim
import random import imageman   const Size = 400 # Area size. MaxXY = Size - 1 # Maximum possible value for x and y. NPart = 25_000 # Number of particles. Background = ColorRGBU [byte 0, 0, 0] # Background color. Foreground = ColorRGBU [byte 50, 150, 255] # Foreground color.   randomize() var image = initImage[ColorRGBU](Size, Size) image.fill(Background) image[Size div 2, Size div 2] = Foreground   for _ in 1..NPart:   block ProcessParticle: while true: # Repeat until the particle is freezed.   # Choose position of particle. var x, y = rand(MaxXY) if image[x, y] == Foreground: continue # Not free. Try again.   # Move the particle. while true:   # Choose a motion. let dx, dy = rand(-1..1) inc x, dx inc y, dy if x notin 0..MaxXY or y notin 0..MaxXY: break # Out of limits. Try again.   # Valid move. if image[x, y] == Foreground: # Not free. Freeze the particle at its previous position. image[x - dx, y - dy] = Foreground break ProcessParticle # Done. Process next particle.   # Save into a PNG file. image.savePNG("brownian.png", compression = 9)
http://rosettacode.org/wiki/Bulls_and_cows
Bulls and cows
Bulls and Cows Task Create a four digit random number from the digits   1   to   9,   without duplication. The program should:   ask for guesses to this number   reject guesses that are malformed   print the score for the guess The score is computed as: The player wins if the guess is the same as the randomly chosen number, and the program ends. A score of one bull is accumulated for each digit in the guess that equals the corresponding digit in the randomly chosen initial number. A score of one cow is accumulated for each digit in the guess that also appears in the randomly chosen number, but in the wrong position. Related tasks   Bulls and cows/Player   Guess the number   Guess the number/With Feedback   Mastermind
#Factor
Factor
USING: accessors assocs combinators fry grouping hashtables kernel locals math math.parser math.ranges random sequences strings io ascii ;   IN: bullsncows   TUPLE: score bulls cows ; : <score> ( -- score ) 0 0 score boa ;   TUPLE: cow ; : <cow> ( -- cow ) cow new ;   TUPLE: bull ; : <bull> ( -- bull ) bull new ;   : inc-bulls ( score -- score ) dup bulls>> 1 + >>bulls ; : inc-cows ( score -- score ) dup cows>> 1 + >>cows ;   : random-nums ( -- seq ) 9 [1,b] 4 sample ;   : add-digits ( seq -- n ) 0 [ swap 10 * + ] reduce number>string ;   : new-number ( -- n narr ) random-nums dup add-digits ;   : narr>nhash ( narr -- nhash ) { 1 2 3 4 } swap zip ;   : num>hash ( n -- hash ) [ 1string string>number ] { } map-as narr>nhash ;   :: cow-or-bull ( n g -- arr ) { { [ n first g at n second = ] [ <bull> ] } { [ n second g value? ] [ <cow> ] } [ f ] } cond ;   : add-to-score ( arr -- score ) <score> [ bull? [ inc-bulls ] [ inc-cows ] if ] reduce ;   : check-win ( score -- ? ) bulls>> 4 = ;   : sum-score ( n g -- score ? ) '[ _ cow-or-bull ] map sift add-to-score dup check-win ;   : print-sum ( score -- str ) dup bulls>> number>string "Bulls: " swap append swap cows>> number>string " Cows: " swap 3append "\n" append ;   : (validate-readln) ( str -- ? ) dup length 4 = not swap [ letter? ] all? or ;   : validate-readln ( -- str ) readln dup (validate-readln) [ "Invalid input.\nPlease enter a valid 4 digit number: " write flush drop validate-readln ] when ;   : win ( -- ) "\nYou've won! Good job. You're so smart." print flush ;   : main-loop ( x -- ) "Enter a 4 digit number: " write flush validate-readln num>hash swap [ sum-score swap print-sum print flush ] keep swap not [ main-loop ] [ drop win ] if ;   : main ( -- ) new-number drop narr>nhash main-loop ;
http://rosettacode.org/wiki/Caesar_cipher
Caesar cipher
Task Implement a Caesar cipher, both encoding and decoding. The key is an integer from 1 to 25. This cipher rotates (either towards left or right) the letters of the alphabet (A to Z). The encoding replaces each letter with the 1st to 25th next letter in the alphabet (wrapping Z to A). So key 2 encrypts "HI" to "JK", but key 20 encrypts "HI" to "BC". This simple "mono-alphabetic substitution cipher" provides almost no security, because an attacker who has the encoded message can either use frequency analysis to guess the key, or just try all 25 keys. Caesar cipher is identical to Vigenère cipher with a key of length 1. Also, Rot-13 is identical to Caesar cipher with key 13. Related tasks Rot-13 Substitution Cipher Vigenère Cipher/Cryptanalysis
#Dart
Dart
class Caesar { int _key;   Caesar(this._key);   int _toCharCode(String s) { return s.charCodeAt(0); }   String _fromCharCode(int ch) { return new String.fromCharCodes([ch]); }   String _process(String msg, int offset) { StringBuffer sb=new StringBuffer(); for(int i=0;i<msg.length;i++) { int ch=msg.charCodeAt(i); if(ch>=_toCharCode('A')&&ch<=_toCharCode('Z')) { sb.add(_fromCharCode(_toCharCode("A")+(ch-_toCharCode("A")+offset)%26)); } else if(ch>=_toCharCode('a')&&ch<=_toCharCode('z')) { sb.add(_fromCharCode(_toCharCode("a")+(ch-_toCharCode("a")+offset)%26)); } else { sb.add(msg[i]); } } return sb.toString(); }   String encrypt(String msg) { return _process(msg, _key); }   String decrypt(String msg) { return _process(msg, 26-_key); } }   void trip(String msg) { Caesar cipher=new Caesar(10);   String enc=cipher.encrypt(msg); String dec=cipher.decrypt(enc); print("\"$msg\" encrypts to:"); print("\"$enc\" decrypts to:"); print("\"$dec\""); Expect.equals(msg,dec); }   main() { Caesar c2=new Caesar(2); print(c2.encrypt("HI")); Caesar c20=new Caesar(20); print(c20.encrypt("HI"));   // try a few roundtrips   trip(""); trip("A"); trip("z"); trip("Caesar cipher"); trip(".-:/\"\\!"); trip("The Quick Brown Fox Jumps Over The Lazy Dog."); }
http://rosettacode.org/wiki/Calculating_the_value_of_e
Calculating the value of e
Task Calculate the value of   e. (e   is also known as   Euler's number   and   Napier's constant.) See details: Calculating the value of e
#R
R
  options(digits=22) cat("e =",sum(rep(1,20)/factorial(0:19)))  
http://rosettacode.org/wiki/Calculating_the_value_of_e
Calculating the value of e
Task Calculate the value of   e. (e   is also known as   Euler's number   and   Napier's constant.) See details: Calculating the value of e
#Quackery
Quackery
$ "bigrat.qky" loadfile   [ swap number$ tuck size - times sp echo$ ] is echo-rj ( n n --> )   [ 2dup swap say " First " echo say " approximations of e by sum of 1/n! displayed to " echo say " decimal places." cr cr temp put 1 n->v rot 1 swap times [ i^ 1+ * dup n->v 1/v rot dip [ v+ 2dup i^ 1+ 5 echo-rj say " : " temp share point$ echo$ cr ] ] 3 times drop temp release ] is approximate-e ( n n --> )   55 70 approximate-e
http://rosettacode.org/wiki/Bulls_and_cows/Player
Bulls and cows/Player
Task Write a player of the Bulls and Cows game, rather than a scorer. The player should give intermediate answers that respect the scores to previous attempts. One method is to generate a list of all possible numbers that could be the answer, then to prune the list by keeping only those numbers that would give an equivalent score to how your last guess was scored. Your next guess can be any number from the pruned list. Either you guess correctly or run out of numbers to guess, which indicates a problem with the scoring. Related tasks   Bulls and cows   Guess the number   Guess the number/With Feedback (Player)
#Shale
Shale
#!/usr/local/bin/shale   maths library file library string library   lista var listb var firstTimeThrough var guess var guess0 var guess1 var guess2 var guess3 var bulls var cows var   init dup var { count a:: var count b:: var } =   randomDigit dup var { random maths::() 18 >> 9 % 1 + } =   makeGuess dup var { firstTimeThrough { guess0 randomDigit() = guess1 randomDigit() = { guess1 guess0 == } { guess1 randomDigit() = } while guess2 randomDigit() = { guess2 guess0 == guess2 guess1 == or } { guess2 randomDigit() = } while guess3 randomDigit() = { guess3 guess0 == guess3 guess1 == guess3 guess2 == or or } { guess3 randomDigit() = } while guess guess3 1000 * guess2 100 * guess1 10 * guess0 + + + = } { i var   i random maths::() count lista->:: % = guess i.value lista->:: value = guess0 guess 10 % = guess1 guess 10 / 10 % = guess2 guess 100 / 10 % = guess3 guess 1000 / = } if } =   getAnswer dup var { stdin file:: fgets file::() { atoi string::() } { 0 exit } if } =   getScore dup var { haveBulls dup var false = haveCows dup var false = ans var   { haveBulls not } { "Bulls: " print ans getAnswer() = ans 0 < ans 4 > and { "Please try again" println } { bulls ans = haveBulls true = } if } while   { haveCows not } { "Cows: " print ans getAnswer() = ans 0 < ans 4 > and { "Please try again" println } { cows ans = haveCows true = } if } while } =   check dup var { d0 dup var swap = // units d1 dup var swap = d2 dup var swap = d3 dup var swap = // thousands b dup var 0 = c dup var 0 =   d0 guess0 == { b++ } { d0 guess1 == { d0 guess2 == { d0 guess3 == } or } or { c++ } ifthen } if d1 guess1 == { b++ } { d1 guess0 == { d1 guess2 == { d1 guess3 == } or } or { c++ } ifthen } if d2 guess2 == { b++ } { d2 guess0 == { d2 guess1 == { d2 guess3 == } or } or { c++ } ifthen } if d3 guess3 == { b++ } { d3 guess0 == { d3 guess1 == { d3 guess2 == } or } or { c++ } ifthen } if   b bulls >= c cows >= and } =   add dup var { n dup var swap =   n guess != { // never put our own guess back in the list. i var   i count listb->:: = i.value listb->:: defined not { i.value listb->:: var } ifthen   i.value listb->:: n = count listb->::++ } ifthen } =   filterList dup var { firstTimeThrough { a var b var c var d var   a 1 = { a 10 < } { b 1 = { b 10 < } { b a != { c 1 = { c 10 < } { c a != c b != and { d 1 = { d 10 < } { d a != { d b != d c != and } and { a b c d check() { a 1000 * b 100 * c 10 * d + + + add() } ifthen } ifthen d++ } while } ifthen c++ } while } ifthen b++ } while a++ } while } { i var j var n var   count listb->:: 0 = i 0 = { i count lista->:: < } { n i.value lista->:: = n 1000 / n 100 / 10 % n 10 / 10 % n 10 % check() { n.value add() } ifthen i++ } while } if } =   solve dup var { t var f var n var   lista a &= listb b &= firstTimeThrough true = count a:: 0 = count b:: 0 =   n 1 = f 1 = { f } { makeGuess() guess0 guess1 guess2 guess3 n "\nGuess %d: %d %d %d %d\n" printf getScore() bulls 4 == { "WooHoo, I won!" println break } ifthen filterList() f count listb->:: =   t lista = lista listb = listb t = firstTimeThrough false = n++ } while   count lista->:: 0 == { "I've run out of numbers to choose from." println } ifthen } =   init() { true } { solve() } while
http://rosettacode.org/wiki/Calendar_-_for_%22REAL%22_programmers
Calendar - for "REAL" programmers
Task Provide an algorithm as per the Calendar task, except the entire code for the algorithm must be presented   entirely without lowercase. Also - as per many 1969 era line printers - format the calendar to nicely fill a page that is 132 characters wide. (Hint: manually convert the code from the Calendar task to all UPPERCASE) This task also is inspired by Real Programmers Don't Use PASCAL by Ed Post, Datamation, volume 29 number 7, July 1983. THE REAL PROGRAMMER'S NATURAL HABITAT "Taped to the wall is a line-printer Snoopy calender for the year 1969." Moreover this task is further inspired by the long lost corollary article titled: "Real programmers think in UPPERCASE"! Note: Whereas today we only need to worry about ASCII, UTF-8, UTF-16, UTF-32, UTF-7 and UTF-EBCDIC encodings, in the 1960s having code in UPPERCASE was often mandatory as characters were often stuffed into 36-bit words as 6 lots of 6-bit characters. More extreme words sizes include 60-bit words of the CDC 6000 series computers. The Soviets even had a national character set that was inclusive of all 4-bit, 5-bit, 6-bit & 7-bit depending on how the file was opened... And one rogue Soviet university went further and built a 1.5-bit based computer. Of course... as us Boomers have turned into Geezers we have become HARD OF HEARING, and suffer from chronic Presbyopia, hence programming in UPPERCASE is less to do with computer architecture and more to do with practically. :-) For economy of size, do not actually include Snoopy generation in either the code or the output, instead just output a place-holder. FYI: a nice ASCII art file of Snoopy can be found at textfiles.com. Save with a .txt extension. Trivia: The terms uppercase and lowercase date back to the early days of the mechanical printing press. Individual metal alloy casts of each needed letter, or punctuation symbol, were meticulously added to a press block, by hand, before rolling out copies of a page. These metal casts were stored and organized in wooden cases. The more often needed minuscule letters were placed closer to hand, in the lower cases of the work bench. The less often needed, capitalized, majuscule letters, ended up in the harder to reach upper cases.
#XLISP
XLISP
(SETQ YR 1969) (SETQ M #("JANUARY" "FEBRUARY" "MARCH" "APRIL" "MAY" "JUNE" "JULY" "AUGUST" "SEPTEMBER" "OCTOBER" "NOVEMBER" "DECEMBER")) (SETQ ML #(31 28 31 30 31 30 31 31 30 31 30 31)) (SETQ WD #("SU" "MO" "TU" "WE" "TH" "FR" "SA")) (IF (AND (= (REM YR 4) 0) (OR (/= (REM YR 100) 0) (= (REM YR 400) 0))) (VECTOR-SET! ML 1 29)) (SETQ D (REM (+ 1 (+ (* 5 (REM (- YR 1) 4)) (* 4 (REM (- YR 1) 100)) (* 6 (REM (- YR 1) 400)))) 7)) (TERPRI) (DO ((I 0 (+ I 1))) ((> I 60)) (PRINC " ")) (PRINC "SNOOPY CALENDAR ") (PRINC YR) (TERPRI) (DO ((I 0 (+ I 1))) ((> I 11)) (TERPRI) (DO ((J 0 (+ J 1))) ((> J 65)) (PRINC " ")) (PRINC (VECTOR-REF M I)) (TERPRI) (PRINC " ") (DO ((J 0 (+ J 1))) ((> J 6)) (DO ((K 0 (+ K 1))) ((> K 14)) (PRINC " ")) (PRINC (VECTOR-REF WD J)) (PRINC " ")) (TERPRI) (DO ((J 0 (+ J 1))) ((> J 6)) (IF (< J D) (DO ((K 0 (+ K 1))) ((> K 18)) (PRINC " ")))) (DO ((J 1 (+ J 1))) ((> J (VECTOR-REF ML I))) (PRINC " ") (IF (< J 10) (PRINC " ")) (DO ((K 0 (+ K 1))) ((> K 14)) (PRINC " ")) (PRINC J) (SETQ D (+ D 1)) (IF (> D 6) (TERPRI)) (IF (> D 6) (SETQ D 0))))
http://rosettacode.org/wiki/Call_a_function
Call a function
Task Demonstrate the different syntax and semantics provided for calling a function. This may include:   Calling a function that requires no arguments   Calling a function with a fixed number of arguments   Calling a function with optional arguments   Calling a function with a variable number of arguments   Calling a function with named arguments   Using a function in statement context   Using a function in first-class context within an expression   Obtaining the return value of a function   Distinguishing built-in functions and user-defined functions   Distinguishing subroutines and functions   Stating whether arguments are passed by value or by reference   Is partial application possible and how This task is not about defining functions.
#i
i
//The type of the function argument determines whether or not the value is passed by reference or not. //Eg. numbers are passed by value and lists/arrays are passed by reference.   software { print() //Calling a function with no arguments. print("Input a number!") //Calling a function with fixed arguments. print(1,2,3,4,5,6,7,8,9,0) //Calling a function with variable arguments. input = read() //Obtaining the return value of a function. myprint = print myprint("It was: ", input) //Calling first class functions, the same as calling ordinary functions.   //The only distinction that can be made between two functions is if they are 'real' or not. if type(myprint) = concept print("myprint is a not a real function") else if type(myprint) = function print("myprint is a real function") end   //Partial functions can be created with static parts. DebugPrint = print["[DEBUG] ", text] DebugPrint("partial function!") //This would output '[DEBUG] partial function!'   if type(DebugPrint) = concept print("DebugPrint is a not a real function") else if type(DebugPrint) = function print("DebugPrint is a real function") end }  
http://rosettacode.org/wiki/Catalan_numbers
Catalan numbers
Catalan numbers You are encouraged to solve this task according to the task description, using any language you may know. Catalan numbers are a sequence of numbers which can be defined directly: C n = 1 n + 1 ( 2 n n ) = ( 2 n ) ! ( n + 1 ) ! n !  for  n ≥ 0. {\displaystyle C_{n}={\frac {1}{n+1}}{2n \choose n}={\frac {(2n)!}{(n+1)!\,n!}}\qquad {\mbox{ for }}n\geq 0.} Or recursively: C 0 = 1 and C n + 1 = ∑ i = 0 n C i C n − i for  n ≥ 0 ; {\displaystyle C_{0}=1\quad {\mbox{and}}\quad C_{n+1}=\sum _{i=0}^{n}C_{i}\,C_{n-i}\quad {\text{for }}n\geq 0;} Or alternatively (also recursive): C 0 = 1 and C n = 2 ( 2 n − 1 ) n + 1 C n − 1 , {\displaystyle C_{0}=1\quad {\mbox{and}}\quad C_{n}={\frac {2(2n-1)}{n+1}}C_{n-1},} Task Implement at least one of these algorithms and print out the first 15 Catalan numbers with each. Memoization   is not required, but may be worth the effort when using the second method above. Related tasks Catalan numbers/Pascal's triangle Evaluate binomial coefficients
#Maxima
Maxima
/* The following is an array function, hence the square brackets. It uses memoization automatically */ cata[n] := sum(cata[i]*cata[n - 1 - i], i, 0, n - 1)$ cata[0]: 1$   cata2(n) := binomial(2*n, n)/(n + 1)$   makelist(cata[n], n, 0, 14);   makelist(cata2(n), n, 0, 14);   /* both return [1, 1, 2, 5, 14, 42, 132, 429, 1430, 4862, 16796, 58786, 208012, 742900, 2674440] */
http://rosettacode.org/wiki/Brace_expansion
Brace expansion
Brace expansion is a type of parameter expansion made popular by Unix shells, where it allows users to specify multiple similar string parameters without having to type them all out. E.g. the parameter enable_{audio,video} would be interpreted as if both enable_audio and enable_video had been specified. Task[edit] Write a function that can perform brace expansion on any input string, according to the following specification. Demonstrate how it would be used, and that it passes the four test cases given below. Specification In the input string, balanced pairs of braces containing comma-separated substrings (details below) represent alternations that specify multiple alternatives which are to appear at that position in the output. In general, one can imagine the information conveyed by the input string as a tree of nested alternations interspersed with literal substrings, as shown in the middle part of the following diagram: It{{em,alic}iz,erat}e{d,} parse  ―――――▶ ‌ It ⎧ ⎨ ⎩ ⎧ ⎨ ⎩ em ⎫ ⎬ ⎭ alic iz ⎫ ⎬ ⎭ erat e ⎧ ⎨ ⎩ d ⎫ ⎬ ⎭ ‌ expand  ―――――▶ ‌ Itemized Itemize Italicized Italicize Iterated Iterate input string alternation tree output (list of strings) This tree can in turn be transformed into the intended list of output strings by, colloquially speaking, determining all the possible ways to walk through it from left to right while only descending into one branch of each alternation one comes across (see the right part of the diagram). When implementing it, one can of course combine the parsing and expansion into a single algorithm, but this specification discusses them separately for the sake of clarity. Expansion of alternations can be more rigorously described by these rules: a ⎧ ⎨ ⎩ 2 ⎫ ⎬ ⎭ 1 b ⎧ ⎨ ⎩ X ⎫ ⎬ ⎭ Y X c ⟶ a2bXc a2bYc a2bXc a1bXc a1bYc a1bXc An alternation causes the list of alternatives that will be produced by its parent branch to be increased 𝑛-fold, each copy featuring one of the 𝑛 alternatives produced by the alternation's child branches, in turn, at that position. This means that multiple alternations inside the same branch are cumulative  (i.e. the complete list of alternatives produced by a branch is the string-concatenating "Cartesian product" of its parts). All alternatives (even duplicate and empty ones) are preserved, and they are ordered like the examples demonstrate  (i.e. "lexicographically" with regard to the alternations). The alternatives produced by the root branch constitute the final output. Parsing the input string involves some additional complexity to deal with escaped characters and "incomplete" brace pairs: a\\{\\\{b,c\,d} ⟶ a\\ ⎧ ⎨ ⎩ \\\{b ⎫ ⎬ ⎭ c\,d {a,b{c{,{d}}e}f ⟶ {a,b{c ⎧ ⎨ ⎩ ‌ ⎫ ⎬ ⎭ {d} e}f An unescaped backslash which precedes another character, escapes that character (to force it to be treated as literal). The backslashes are passed along to the output unchanged. Balanced brace pairs are identified by, conceptually, going through the string from left to right and associating each unescaped closing brace that is encountered with the nearest still unassociated unescaped opening brace to its left (if any). Furthermore, each unescaped comma is associated with the innermost brace pair that contains it (if any). With that in mind: Each brace pair that has at least one comma associated with it, forms an alternation (whose branches are the brace pair's contents split at its commas). The associated brace and comma characters themselves do not become part of the output. Brace characters from pairs without any associated comma, as well as unassociated brace and comma characters, as well as all characters that are not covered by the preceding rules, are instead treated as literals. For every possible input string, your implementation should produce exactly the output which this specification mandates. Please comply with this even when it's inconvenient, to ensure that all implementations are comparable. However, none of the above should be interpreted as instructions (or even recommendations) for how to implement it. Try to come up with a solution that is idiomatic in your programming language. (See #Perl for a reference implementation.) Test Cases Input (single string) Ouput (list/array of strings) ~/{Downloads,Pictures}/*.{jpg,gif,png} ~/Downloads/*.jpg ~/Downloads/*.gif ~/Downloads/*.png ~/Pictures/*.jpg ~/Pictures/*.gif ~/Pictures/*.png It{{em,alic}iz,erat}e{d,}, please. Itemized, please. Itemize, please. Italicized, please. Italicize, please. Iterated, please. Iterate, please. {,{,gotta have{ ,\, again\, }}more }cowbell! cowbell! more cowbell! gotta have more cowbell! gotta have\, again\, more cowbell! {}} some }{,{\\{ edge, edge} \,}{ cases, {here} \\\\\} {}} some }{,{\\ edge \,}{ cases, {here} \\\\\} {}} some }{,{\\ edge \,}{ cases, {here} \\\\\} Other tasks related to string operations: Metrics Array length String length Copy a string Empty string  (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff  (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet   Brace_expansion_using_ranges
#Rust
Rust
const OPEN_CHAR: char = '{'; const CLOSE_CHAR: char = '}'; const SEPARATOR: char = ','; const ESCAPE: char = '\\';   #[derive(Debug, PartialEq, Clone)] enum Token { Open, Close, Separator, Payload(String), Branches(Branches), }   impl From<char> for Token { fn from(ch: char) -> Token { match ch { OPEN_CHAR => Token::Open, CLOSE_CHAR => Token::Close, SEPARATOR => Token::Separator, _ => panic!("Non tokenizable char!"), } } }   #[derive(Debug, PartialEq, Clone)] struct Branches { tokens: Vec<Vec<Token>>, }   impl Branches { fn new() -> Branches { Branches{ tokens: Vec::new(), } }   fn add_branch(&mut self, branch: Vec<Token>) { self.tokens.push(branch); }   fn from(tokens: &Vec<Token>) -> Branches { let mut branches = Branches::new(); let mut tail = tokens.clone(); while let Some(pos) = tail.iter().position(|token| { *token == Token::Separator }) { let mut rest = tail.split_off(pos); branches.add_branch(tail); rest.remove(0); tail = rest; } branches.add_branch(tail); branches } }   impl From<Branches> for Token { fn from(branches: Branches) -> Token { Token::Branches(branches) } }   impl From<Vec<Token>> for Branches { fn from(tokens: Vec<Token>) -> Branches { Branches::from(&tokens) } }   impl From<Token> for String { fn from(token: Token) -> String { match token { Token::Branches(_) => panic!("Cannot convert to String!"), Token::Payload(text) => text, Token::Open => OPEN_CHAR.to_string(), Token::Close => CLOSE_CHAR.to_string(), Token::Separator => SEPARATOR.to_string(), } } }   impl From<Branches> for Vec<String> { fn from(branches: Branches) -> Vec<String> { let Branches{ tokens: token_lines } = branches; let mut vec: Vec<String> = Vec::new(); let braces = { if token_lines.len() == 1 { true } else { false } }; for tokens in token_lines { let mut vec_string = output(tokens); vec.append(&mut vec_string); } if braces { vec.iter() .map(|line| { format!("{}{}{}", OPEN_CHAR, line, CLOSE_CHAR) }). collect::<Vec<String>>() } else { vec } } }   impl From<Token> for Vec<String> { fn from(token: Token) -> Vec<String> { match token { Token::Branches(branches) => { branches.into() }, _ => { let frag: String = token.into(); vec![frag] }, } } }   fn tokenize(string: &str) -> Vec<Token> { let mut tokens: Vec<Token> = Vec::new(); let mut chars = string.chars(); let mut payload = String::new(); while let Some(ch) = chars.next() { match ch { OPEN_CHAR | SEPARATOR | CLOSE_CHAR => { if payload.len() > 0 { tokens.push(Token::Payload(payload)); } payload = String::new(); if ch == CLOSE_CHAR { let pos = tokens.iter().rposition(|token| *token == Token::Open); if let Some(pos) = pos { let branches: Branches = { let mut to_branches = tokens.split_off(pos); to_branches.remove(0); to_branches }.into(); tokens.push(branches.into()); } else { tokens.push(ch.into()); } } else { tokens.push(ch.into()); } }, ESCAPE => { payload.push(ch); if let Some(next_char) = chars.next() { payload.push(next_char); } }, _ => payload.push(ch), } } let payload = payload.trim_end(); if payload.len() > 0 { tokens.push(Token::Payload(payload.into())); } tokens }   fn output(tokens: Vec<Token>) -> Vec<String> { let mut output: Vec<String> = vec![String::new()]; for token in tokens { let mut aux: Vec<String> = Vec::new(); let strings: Vec<String> = token.into(); for root in &output { for string in &strings { aux.push({format!("{}{}", root, string)}); } } output = aux; } output }   fn main() { let mut input: String = String::new(); std::io::stdin().read_line(&mut input).unwrap();   let tokens: Vec<Token> = tokenize(&input); // println!("Tokens:\n{:#?}", tokens);   let output = output(tokens); for line in &output { println!("{}", line); } }
http://rosettacode.org/wiki/Brace_expansion
Brace expansion
Brace expansion is a type of parameter expansion made popular by Unix shells, where it allows users to specify multiple similar string parameters without having to type them all out. E.g. the parameter enable_{audio,video} would be interpreted as if both enable_audio and enable_video had been specified. Task[edit] Write a function that can perform brace expansion on any input string, according to the following specification. Demonstrate how it would be used, and that it passes the four test cases given below. Specification In the input string, balanced pairs of braces containing comma-separated substrings (details below) represent alternations that specify multiple alternatives which are to appear at that position in the output. In general, one can imagine the information conveyed by the input string as a tree of nested alternations interspersed with literal substrings, as shown in the middle part of the following diagram: It{{em,alic}iz,erat}e{d,} parse  ―――――▶ ‌ It ⎧ ⎨ ⎩ ⎧ ⎨ ⎩ em ⎫ ⎬ ⎭ alic iz ⎫ ⎬ ⎭ erat e ⎧ ⎨ ⎩ d ⎫ ⎬ ⎭ ‌ expand  ―――――▶ ‌ Itemized Itemize Italicized Italicize Iterated Iterate input string alternation tree output (list of strings) This tree can in turn be transformed into the intended list of output strings by, colloquially speaking, determining all the possible ways to walk through it from left to right while only descending into one branch of each alternation one comes across (see the right part of the diagram). When implementing it, one can of course combine the parsing and expansion into a single algorithm, but this specification discusses them separately for the sake of clarity. Expansion of alternations can be more rigorously described by these rules: a ⎧ ⎨ ⎩ 2 ⎫ ⎬ ⎭ 1 b ⎧ ⎨ ⎩ X ⎫ ⎬ ⎭ Y X c ⟶ a2bXc a2bYc a2bXc a1bXc a1bYc a1bXc An alternation causes the list of alternatives that will be produced by its parent branch to be increased 𝑛-fold, each copy featuring one of the 𝑛 alternatives produced by the alternation's child branches, in turn, at that position. This means that multiple alternations inside the same branch are cumulative  (i.e. the complete list of alternatives produced by a branch is the string-concatenating "Cartesian product" of its parts). All alternatives (even duplicate and empty ones) are preserved, and they are ordered like the examples demonstrate  (i.e. "lexicographically" with regard to the alternations). The alternatives produced by the root branch constitute the final output. Parsing the input string involves some additional complexity to deal with escaped characters and "incomplete" brace pairs: a\\{\\\{b,c\,d} ⟶ a\\ ⎧ ⎨ ⎩ \\\{b ⎫ ⎬ ⎭ c\,d {a,b{c{,{d}}e}f ⟶ {a,b{c ⎧ ⎨ ⎩ ‌ ⎫ ⎬ ⎭ {d} e}f An unescaped backslash which precedes another character, escapes that character (to force it to be treated as literal). The backslashes are passed along to the output unchanged. Balanced brace pairs are identified by, conceptually, going through the string from left to right and associating each unescaped closing brace that is encountered with the nearest still unassociated unescaped opening brace to its left (if any). Furthermore, each unescaped comma is associated with the innermost brace pair that contains it (if any). With that in mind: Each brace pair that has at least one comma associated with it, forms an alternation (whose branches are the brace pair's contents split at its commas). The associated brace and comma characters themselves do not become part of the output. Brace characters from pairs without any associated comma, as well as unassociated brace and comma characters, as well as all characters that are not covered by the preceding rules, are instead treated as literals. For every possible input string, your implementation should produce exactly the output which this specification mandates. Please comply with this even when it's inconvenient, to ensure that all implementations are comparable. However, none of the above should be interpreted as instructions (or even recommendations) for how to implement it. Try to come up with a solution that is idiomatic in your programming language. (See #Perl for a reference implementation.) Test Cases Input (single string) Ouput (list/array of strings) ~/{Downloads,Pictures}/*.{jpg,gif,png} ~/Downloads/*.jpg ~/Downloads/*.gif ~/Downloads/*.png ~/Pictures/*.jpg ~/Pictures/*.gif ~/Pictures/*.png It{{em,alic}iz,erat}e{d,}, please. Itemized, please. Itemize, please. Italicized, please. Italicize, please. Iterated, please. Iterate, please. {,{,gotta have{ ,\, again\, }}more }cowbell! cowbell! more cowbell! gotta have more cowbell! gotta have\, again\, more cowbell! {}} some }{,{\\{ edge, edge} \,}{ cases, {here} \\\\\} {}} some }{,{\\ edge \,}{ cases, {here} \\\\\} {}} some }{,{\\ edge \,}{ cases, {here} \\\\\} Other tasks related to string operations: Metrics Array length String length Copy a string Empty string  (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff  (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet   Brace_expansion_using_ranges
#Scala
Scala
  import collection.mutable.ListBuffer case class State(isChild: Boolean, alts: ListBuffer[String], rem: List[Char]) def expand(s: String): Seq[String] = { def parseGroup(s: State): State = s.rem match { case Nil => s.copy(alts = ListBuffer("{" + s.alts.mkString(","))) case ('{' | ',')::sp => val newS = State(true, ListBuffer(""), rem = sp) val elem = parseElem(newS) elem.rem match { case Nil => elem.copy(alts = elem.alts.map(a => "{" + s.alts.map(_ + ",").mkString("") + a)) case elemrem => parseGroup(s.copy(alts = (s.alts ++= elem.alts), rem = elem.rem)) } case '}'::sp => if (s.alts.isEmpty) s.copy(alts = ListBuffer("{}"), rem = sp) else if(s.alts.length == 1) s.copy(alts = ListBuffer("{"+s.alts.head + "}"), rem = sp) else s.copy(rem = sp) case _ => throw new Exception("parseGroup should be called only with delimitors") } def parseElem(s: State): State = s.rem match { case Nil => s case '{'::sp => val ys = parseGroup(State(true, ListBuffer(), s.rem)) val newAlts = for { x <- s.alts; y <- ys.alts} yield x + y parseElem(s.copy(alts = newAlts, rem = ys.rem)) case (',' | '}')::_ if s.isChild => s case '\\'::c::sp => parseElem(s.copy(alts = s.alts.map(_ + '\\' + c), rem = sp)) case c::sp => parseElem(s.copy(alts = s.alts.map(_ + c), rem = sp)) } parseElem(State(false, ListBuffer(""), s.toList)).alts }  
http://rosettacode.org/wiki/Brazilian_numbers
Brazilian numbers
Brazilian numbers are so called as they were first formally presented at the 1994 math Olympiad Olimpiada Iberoamericana de Matematica in Fortaleza, Brazil. Brazilian numbers are defined as: The set of positive integer numbers where each number N has at least one natural number B where 1 < B < N-1 where the representation of N in base B has all equal digits. E.G. 1, 2 & 3 can not be Brazilian; there is no base B that satisfies the condition 1 < B < N-1. 4 is not Brazilian; 4 in base 2 is 100. The digits are not all the same. 5 is not Brazilian; 5 in base 2 is 101, in base 3 is 12. There is no representation where the digits are the same. 6 is not Brazilian; 6 in base 2 is 110, in base 3 is 20, in base 4 is 12. There is no representation where the digits are the same. 7 is Brazilian; 7 in base 2 is 111. There is at least one representation where the digits are all the same. 8 is Brazilian; 8 in base 3 is 22. There is at least one representation where the digits are all the same. and so on... All even integers 2P >= 8 are Brazilian because 2P = 2(P-1) + 2, which is 22 in base P-1 when P-1 > 2. That becomes true when P >= 4. More common: for all all integers R and S, where R > 1 and also S-1 > R, then R*S is Brazilian because R*S = R(S-1) + R, which is RR in base S-1 The only problematic numbers are squares of primes, where R = S. Only 11^2 is brazilian to base 3. All prime integers, that are brazilian, can only have the digit 1. Otherwise one could factor out the digit, therefore it cannot be a prime number. Mostly in form of 111 to base Integer(sqrt(prime number)). Must be an odd count of 1 to stay odd like primes > 2 Task Write a routine (function, whatever) to determine if a number is Brazilian and use the routine to show here, on this page; the first 20 Brazilian numbers; the first 20 odd Brazilian numbers; the first 20 prime Brazilian numbers; See also OEIS:A125134 - Brazilian numbers OEIS:A257521 - Odd Brazilian numbers OEIS:A085104 - Prime Brazilian numbers
#Mathematica_.2F_Wolfram_Language
Mathematica / Wolfram Language
brazilianQ[n_Integer /; n>6 ] := AnyTrue[ Range[2, n-2], MatchQ[IntegerDigits[n, #], {x_ ...}] & ] Select[Range[100], brazilianQ, 20] Select[Range[100], brazilianQ@# && OddQ@# &, 20] Select[Range[10000], brazilianQ@# && PrimeQ@# &, 20]  
http://rosettacode.org/wiki/Calendar
Calendar
Create a routine that will generate a text calendar for any year. Test the calendar by generating a calendar for the year 1969, on a device of the time. Choose one of the following devices: A line printer with a width of 132 characters. An IBM 3278 model 4 terminal (80×43 display with accented characters). Target formatting the months of the year to fit nicely across the 80 character width screen. Restrict number of lines in test output to 43. (Ideally, the program will generate well-formatted calendars for any page width from 20 characters up.) Kudos (κῦδος) for routines that also transition from Julian to Gregorian calendar. This task is inspired by Real Programmers Don't Use PASCAL by Ed Post, Datamation, volume 29 number 7, July 1983. THE REAL PROGRAMMER'S NATURAL HABITAT "Taped to the wall is a line-printer Snoopy calender for the year 1969." For further Kudos see task CALENDAR, where all code is to be in UPPERCASE. For economy of size, do not actually include Snoopy generation in either the code or the output, instead just output a place-holder. Related task   Five weekends
#JavaScript
JavaScript
/** * Given a width, return a function that takes a string, and * pads it at both ends to the given width * @param {number} width * @returns {function(string): string} */ const printCenter = width => s => s.padStart(width / 2 + s.length / 2, ' ').padEnd(width);   /** * Given an locale string and options, return a function that takes a date * object, and retrurns the date formatted to the locale and options. * @param {string} locale * @param {DateTimeFormatOptions} options * @returns {function(Date): string} */ const localeName = (locale, options) => { const formatter = new Intl.DateTimeFormat(locale, options); return date => formatter.format(date); };   /** * Increment the date by number. * @param {Date} date * @param {number} inc * @returns {Date} */ const addDay = (date, inc = 1) => { const res = new Date(date.valueOf()); res.setDate(date.getDate() + inc); return res; }   /** * Given a date, build a string of the week, and return it along with * the mutated date object. * @param {Date} date * @returns {[boolean, Date, string]} */ const makeWeek = date => { const month = date.getMonth(); let [wdi, md, m] = [date.getUTCDay(), date.getDate(), date.getMonth()]; const line = Array(7).fill(' ').map((e, i) => { if (i === wdi && m === month) { const result = (md + '').padStart(2, ' '); date = addDay(date); [wdi, md, m] = [date.getUTCDay(), date.getDate(), date.getMonth()]; return result; } else { return e; } }).join(' '); return [month !== m, date, line]; }   /** * Print a nicely formatted calender for the given year in the given locale. * @param {number} year The required year of the calender * @param {string} locale The locale string. Defaults to US English. * @param {number} cols The number of columns for the months. Defaults to 3. * @param {number} coll_space The space between the columns. Defaults to 5. */ const cal = (year, locale = 'en-US', cols = 3, coll_space = 5) => { const MONTH_LINES = 9; // Number of lines that make up a month. const MONTH_COL_WIDTH = 20; // Character width of a month const COL_SPACE = ' '.padStart(coll_space); const FULL_WIDTH = MONTH_COL_WIDTH * cols + coll_space * (cols - 1);   const collArr = Array(cols).fill(''); const monthName = localeName(locale, {month: 'long'}); const weekDayShort = localeName(locale, {weekday: 'short'}); const monthCenter = printCenter(MONTH_COL_WIDTH); const pageCenter = printCenter(FULL_WIDTH);   // Get the weekday in the given locale. const sun = new Date(Date.UTC(2017, 0, 1)); // A sunday const weekdays = Array(7).fill('').map((e, i) => weekDayShort(addDay(sun, i)).padStart(2, ' ').substring(0, 2)).join(' ');   // The start date. let date = new Date(Date.UTC(year, 0, 1, 0, 0, 0)); let nextMonth = true; let line = ''; const fullYear = date.getUTCFullYear();   // The array into which each of the lines are populated. const accumulate = [];   // Populate the month table heading and columns. const preAmble = date => { accumulate.push(monthCenter(' ')) accumulate.push(monthCenter(monthName(date))); accumulate.push(weekdays); };   // Accumulate the week lines for the year. while (date.getUTCFullYear() === fullYear) { if (nextMonth) { if (accumulate.length % MONTH_LINES !== 0) { accumulate.push(monthCenter(' ')) } preAmble(date); } [nextMonth, date, line] = makeWeek(date); accumulate.push(line); }   // Print the calendar. console.log(pageCenter(String.fromCodePoint(0x1F436))); console.log(pageCenter(`--- ${fullYear} ---`)); accumulate.reduce((p, e, i) => { if (!p.includes(i)) { const indexes = collArr.map((e, ci) => i + ci * MONTH_LINES); console.log(indexes.map(e => accumulate[e]).join(COL_SPACE)); p.push(...indexes); } return p; }, []); };   cal(1969, 'en-US', 3);  
http://rosettacode.org/wiki/Brownian_tree
Brownian tree
Brownian tree You are encouraged to solve this task according to the task description, using any language you may know. Task Generate and draw a   Brownian Tree. A Brownian Tree is generated as a result of an initial seed, followed by the interaction of two processes. The initial "seed" is placed somewhere within the field. Where is not particularly important; it could be randomized, or it could be a fixed point. Particles are injected into the field, and are individually given a (typically random) motion pattern. When a particle collides with the seed or tree, its position is fixed, and it's considered to be part of the tree. Because of the lax rules governing the random nature of the particle's placement and motion, no two resulting trees are really expected to be the same, or even necessarily have the same general shape.
#OCaml
OCaml
let world_width = 400 let world_height = 400 let num_particles = 20_000   let () = assert(num_particles > 0); assert(world_width * world_height > num_particles); ;;   let dla ~world = (* put the tree seed *) world.(world_height / 2).(world_width / 2) <- 1;   for i = 1 to num_particles do (* looping helper function *) let rec aux px py = (* randomly choose a direction *) let dx = (Random.int 3) - 1 (* offsets *) and dy = (Random.int 3) - 1 in   if dx + px < 0 || dx + px >= world_width || dy + py < 0 || dy + py >= world_height then (* plop the particle into some other random location *) aux (Random.int world_width) (Random.int world_height) else if world.(py + dy).(px + dx) <> 0 then (* bumped into something, particle set *) world.(py).(px) <- 1 else aux (px + dx) (py + dy) in (* set particle's initial position *) aux (Random.int world_width) (Random.int world_height) done   let to_pbm ~world = print_endline "P1"; (* Type=Portable bitmap, Encoding=ASCII *) Printf.printf "%d %d\n" world_width world_height; Array.iter (fun line -> Array.iter print_int line; print_newline() ) world   let () = Random.self_init(); let world = Array.make_matrix world_width world_height 0 in dla ~world; to_pbm ~world; ;;
http://rosettacode.org/wiki/Bulls_and_cows
Bulls and cows
Bulls and Cows Task Create a four digit random number from the digits   1   to   9,   without duplication. The program should:   ask for guesses to this number   reject guesses that are malformed   print the score for the guess The score is computed as: The player wins if the guess is the same as the randomly chosen number, and the program ends. A score of one bull is accumulated for each digit in the guess that equals the corresponding digit in the randomly chosen initial number. A score of one cow is accumulated for each digit in the guess that also appears in the randomly chosen number, but in the wrong position. Related tasks   Bulls and cows/Player   Guess the number   Guess the number/With Feedback   Mastermind
#Fan
Fan
** ** Bulls and cows. A game pre-dating, and similar to, Mastermind. ** class BullsAndCows {   Void main() { digits := [1,2,3,4,5,6,7,8,9] size := 4 chosen := [,] size.times { chosen.add(digits.removeAt(Int.random(0..<digits.size))) }   echo("I've chosen $size unique digits from 1 to 9 at random. Try to guess my number!") guesses := 0 while (true) // game loop { guesses += 1 guess := Int[,] while (true) // input loop { // get a good guess Sys.out.print("\nNext guess [$guesses]: ") Sys.out.flush inString := Sys.in.readLine?.trim ?: "" inString.each |ch| { if (ch >= '1' && ch <= '9' && !guess.contains(ch)) guess.add(ch-'0') } if (guess.size == 4) break // input loop echo("Oops, try again. You need to enter $size unique digits from 1 to 9") } if (guess.all |v, i->Bool| { return v == chosen[i] }) { echo("\nCongratulations! You guessed correctly in $guesses guesses") break // game loop } bulls := 0 cows  := 0 (0 ..< size).each |i| { if (guess[i] == chosen[i]) bulls += 1 else if (chosen.contains(guess[i])) cows += 1 } echo("\n $bulls Bulls\n $cows Cows") } } }
http://rosettacode.org/wiki/Caesar_cipher
Caesar cipher
Task Implement a Caesar cipher, both encoding and decoding. The key is an integer from 1 to 25. This cipher rotates (either towards left or right) the letters of the alphabet (A to Z). The encoding replaces each letter with the 1st to 25th next letter in the alphabet (wrapping Z to A). So key 2 encrypts "HI" to "JK", but key 20 encrypts "HI" to "BC". This simple "mono-alphabetic substitution cipher" provides almost no security, because an attacker who has the encoded message can either use frequency analysis to guess the key, or just try all 25 keys. Caesar cipher is identical to Vigenère cipher with a key of length 1. Also, Rot-13 is identical to Caesar cipher with key 13. Related tasks Rot-13 Substitution Cipher Vigenère Cipher/Cryptanalysis
#Delphi
Delphi
func Char.Encrypt(code) { if !this.IsLetter() { return this } var offset = (this.IsUpper() ? 'A' : 'a').Order() return Char((this.Order() + code - offset) % 26 + offset) }   func String.Encrypt(code) { var xs = [] for c in this { xs.Add(c.Encrypt(code)) } return String.Concat(values: xs) }   func String.Decrypt(code) { this.Encrypt(26 - code); }   var str = "Pack my box with five dozen liquor jugs." print(str) str = str.Encrypt(5) print("Encrypted: \(str)") str = str.Decrypt(5) print("Decrypted: \(str)")
http://rosettacode.org/wiki/Calculating_the_value_of_e
Calculating the value of e
Task Calculate the value of   e. (e   is also known as   Euler's number   and   Napier's constant.) See details: Calculating the value of e
#Racket
Racket
#lang racket (require math/number-theory)   (define (calculate-e (terms 20)) (apply + (map (compose / factorial) (range terms))))   (module+ main (let ((e (calculate-e))) (displayln e) (displayln (real->decimal-string e 20)) (displayln (real->decimal-string (- (exp 1) e) 20))))
http://rosettacode.org/wiki/Calculating_the_value_of_e
Calculating the value of e
Task Calculate the value of   e. (e   is also known as   Euler's number   and   Napier's constant.) See details: Calculating the value of e
#Raku
Raku
# If you need high precision: Sum of a Taylor series method. # Adjust the terms parameter to suit. Theoretically the # terms could be ∞. Practically, calculating an infinite # series takes an awfully long time so limit to 500.   sub postfix:<!> (Int $n) { (constant f = 1, |[\*] 1..*)[$n] } sub 𝑒 (Int $terms) { sum map { FatRat.new(1,.!) }, ^$terms }   say 𝑒(500).comb(80).join: "\n";   say '';   # Or, if you don't need high precision, it's a built-in. say e;
http://rosettacode.org/wiki/Bulls_and_cows/Player
Bulls and cows/Player
Task Write a player of the Bulls and Cows game, rather than a scorer. The player should give intermediate answers that respect the scores to previous attempts. One method is to generate a list of all possible numbers that could be the answer, then to prune the list by keeping only those numbers that would give an equivalent score to how your last guess was scored. Your next guess can be any number from the pruned list. Either you guess correctly or run out of numbers to guess, which indicates a problem with the scoring. Related tasks   Bulls and cows   Guess the number   Guess the number/With Feedback (Player)
#Sidef
Sidef
# Build a list of all possible solutions. The regular expression weeds # out numbers containing zeroes or repeated digits. var candidates = (1234..9876 -> grep {|n| !("#{n}" =~ /0 | (\d) .*? \1 /x) }.map{.digits});   # Repeatedly prompt for input until the user supplies a reasonable score. # The regex validates the user's input and then returns two numbers. func read_score(guess) { loop { "My guess: %s (from %d possibilities)\n" \ -> printf(guess.join, candidates.len);   if (var m = (Sys.scanln("bulls cows: ") =~ /^\h*(\d)\h*(\d)\h*$/)) { var (bulls, cows) = m.cap.map{.to_i}...; bulls+cows <= 4 && return(bulls, cows); }   say "Please specify the number of bulls and the number of cows"; } }   func score_correct(a, b, bulls, cows) { var (exact, loose) = (0, 0);   for i in ^4 { a[i] == b[i] ? ++exact  : (a[i]~~b && ++loose) }   (bulls == exact) && (cows == loose) }   # Pick a number, display it, get the score, and discard candidates # that don't match the score: loop { var guess = candidates.pick; var (bulls, cows) = read_score(guess); candidates.grep!{|n| score_correct(n, guess, bulls, cows) } candidates.len > 1 || break }   # Print the secret number or the error message ( candidates.len == 1 ? ("Your secret number is: %d" % candidates[0].join)  : ("I think you made a mistake with your scoring") )->say
http://rosettacode.org/wiki/Calendar_-_for_%22REAL%22_programmers
Calendar - for "REAL" programmers
Task Provide an algorithm as per the Calendar task, except the entire code for the algorithm must be presented   entirely without lowercase. Also - as per many 1969 era line printers - format the calendar to nicely fill a page that is 132 characters wide. (Hint: manually convert the code from the Calendar task to all UPPERCASE) This task also is inspired by Real Programmers Don't Use PASCAL by Ed Post, Datamation, volume 29 number 7, July 1983. THE REAL PROGRAMMER'S NATURAL HABITAT "Taped to the wall is a line-printer Snoopy calender for the year 1969." Moreover this task is further inspired by the long lost corollary article titled: "Real programmers think in UPPERCASE"! Note: Whereas today we only need to worry about ASCII, UTF-8, UTF-16, UTF-32, UTF-7 and UTF-EBCDIC encodings, in the 1960s having code in UPPERCASE was often mandatory as characters were often stuffed into 36-bit words as 6 lots of 6-bit characters. More extreme words sizes include 60-bit words of the CDC 6000 series computers. The Soviets even had a national character set that was inclusive of all 4-bit, 5-bit, 6-bit & 7-bit depending on how the file was opened... And one rogue Soviet university went further and built a 1.5-bit based computer. Of course... as us Boomers have turned into Geezers we have become HARD OF HEARING, and suffer from chronic Presbyopia, hence programming in UPPERCASE is less to do with computer architecture and more to do with practically. :-) For economy of size, do not actually include Snoopy generation in either the code or the output, instead just output a place-holder. FYI: a nice ASCII art file of Snoopy can be found at textfiles.com. Save with a .txt extension. Trivia: The terms uppercase and lowercase date back to the early days of the mechanical printing press. Individual metal alloy casts of each needed letter, or punctuation symbol, were meticulously added to a press block, by hand, before rolling out copies of a page. These metal casts were stored and organized in wooden cases. The more often needed minuscule letters were placed closer to hand, in the lower cases of the work bench. The less often needed, capitalized, majuscule letters, ended up in the harder to reach upper cases.
#zkl
zkl
VAR [CONST] D=TIME.DATE, DAYS="SU MO TU WE TH FR SA";   FCN CENTER(TEXT,M) { STRING(" "*((M-TEXT.LEN())/2),TEXT) }   FCN ONEMONTH(YEAR,MONTH){ DAY1:=D.ZELLER(YEAR,MONTH,1); //1969-1-1 -->3 (WED, ISO 8601) DAYZ:=D.DAYSINMONTH(YEAR,MONTH); //1969-1 -->31 LIST(CENTER(D.MONTHNAMES[MONTH],DAYS.LEN()),DAYS).EXTEND( (1).PUMP(DAYZ,(0).PUMP(DAY1,LIST,T(VOID,""))).APPLY("%2S ".FMT) .PUMP(LIST,T(VOID.READ,DAYS.LEN()/3,FALSE),STRING.CREATE)); } ...
http://rosettacode.org/wiki/Call_a_function
Call a function
Task Demonstrate the different syntax and semantics provided for calling a function. This may include:   Calling a function that requires no arguments   Calling a function with a fixed number of arguments   Calling a function with optional arguments   Calling a function with a variable number of arguments   Calling a function with named arguments   Using a function in statement context   Using a function in first-class context within an expression   Obtaining the return value of a function   Distinguishing built-in functions and user-defined functions   Distinguishing subroutines and functions   Stating whether arguments are passed by value or by reference   Is partial application possible and how This task is not about defining functions.
#Icon_and_Unicon
Icon and Unicon
procedure main() # demonstrate and describe function calling syntax and semantics   # normal procedure/function calling   f() # no arguments, also command context f(x) # fixed number of arguments f(x,h,w) # variable number of arguments (varargs) y := f(x) # Obtaining the returned value of a function   # procedures as first class values and string invocation   f!L # Alternate calling syntax using a list as args (if \x then f else g)() # call (f or g)() f := write # assign a procedure f("Write is now called") # ... and call it "f"() # string invocation, procedure "-"(1) # string invocation, operator   # Co-expressions   f{e1,e2} # parallel evaluation co-expression call # equivalent to f([create e1, create e2]) expr @ coexp # transmission of a single value to a coexpression [e1,e2]@coexp # ... of multiple values (list) to a coexpression coexp(e1,e2) # ... same as above but only in Unicon   # Other   f("x:=",1,"y:=",2) # named parameters (user defined) end
http://rosettacode.org/wiki/Catalan_numbers
Catalan numbers
Catalan numbers You are encouraged to solve this task according to the task description, using any language you may know. Catalan numbers are a sequence of numbers which can be defined directly: C n = 1 n + 1 ( 2 n n ) = ( 2 n ) ! ( n + 1 ) ! n !  for  n ≥ 0. {\displaystyle C_{n}={\frac {1}{n+1}}{2n \choose n}={\frac {(2n)!}{(n+1)!\,n!}}\qquad {\mbox{ for }}n\geq 0.} Or recursively: C 0 = 1 and C n + 1 = ∑ i = 0 n C i C n − i for  n ≥ 0 ; {\displaystyle C_{0}=1\quad {\mbox{and}}\quad C_{n+1}=\sum _{i=0}^{n}C_{i}\,C_{n-i}\quad {\text{for }}n\geq 0;} Or alternatively (also recursive): C 0 = 1 and C n = 2 ( 2 n − 1 ) n + 1 C n − 1 , {\displaystyle C_{0}=1\quad {\mbox{and}}\quad C_{n}={\frac {2(2n-1)}{n+1}}C_{n-1},} Task Implement at least one of these algorithms and print out the first 15 Catalan numbers with each. Memoization   is not required, but may be worth the effort when using the second method above. Related tasks Catalan numbers/Pascal's triangle Evaluate binomial coefficients
#Modula-2
Modula-2
MODULE CatalanNumbers; FROM FormatString IMPORT FormatString; FROM Terminal IMPORT WriteString,WriteLn,ReadChar;   PROCEDURE binomial(m,n : LONGCARD) : LONGCARD; VAR r,d : LONGCARD; BEGIN r := 1; d := m - n; IF d>n THEN n := d; d := m - n; END; WHILE m>n DO r := r * m; DEC(m); WHILE (d>1) AND NOT (r MOD d # 0) DO r := r DIV d; DEC(d) END END; RETURN r END binomial;   PROCEDURE catalan1(n : LONGCARD) : LONGCARD; BEGIN RETURN binomial(2*n,n) DIV (1+n) END catalan1;   PROCEDURE catalan2(n : LONGCARD) : LONGCARD; VAR i,sum : LONGCARD; BEGIN IF n>1 THEN sum := 0; FOR i:=0 TO n-1 DO sum := sum + catalan2(i) * catalan2(n - 1 - i) END; RETURN sum ELSE RETURN 1 END END catalan2;   PROCEDURE catalan3(n : LONGCARD) : LONGCARD; BEGIN IF n#0 THEN RETURN 2 *(2 * n - 1) * catalan3(n - 1) DIV (1 + n) ELSE RETURN 1 END END catalan3;   VAR blah : LONGCARD = 123; buf : ARRAY[0..63] OF CHAR; i : LONGCARD; BEGIN FormatString("\tdirect\tsumming\tfrac\n", buf); WriteString(buf); FOR i:=0 TO 15 DO FormatString("%u\t%u\t%u\t%u\n", buf, i, catalan1(i), catalan2(i), catalan3(i)); WriteString(buf) END; ReadChar END CatalanNumbers.
http://rosettacode.org/wiki/Brace_expansion
Brace expansion
Brace expansion is a type of parameter expansion made popular by Unix shells, where it allows users to specify multiple similar string parameters without having to type them all out. E.g. the parameter enable_{audio,video} would be interpreted as if both enable_audio and enable_video had been specified. Task[edit] Write a function that can perform brace expansion on any input string, according to the following specification. Demonstrate how it would be used, and that it passes the four test cases given below. Specification In the input string, balanced pairs of braces containing comma-separated substrings (details below) represent alternations that specify multiple alternatives which are to appear at that position in the output. In general, one can imagine the information conveyed by the input string as a tree of nested alternations interspersed with literal substrings, as shown in the middle part of the following diagram: It{{em,alic}iz,erat}e{d,} parse  ―――――▶ ‌ It ⎧ ⎨ ⎩ ⎧ ⎨ ⎩ em ⎫ ⎬ ⎭ alic iz ⎫ ⎬ ⎭ erat e ⎧ ⎨ ⎩ d ⎫ ⎬ ⎭ ‌ expand  ―――――▶ ‌ Itemized Itemize Italicized Italicize Iterated Iterate input string alternation tree output (list of strings) This tree can in turn be transformed into the intended list of output strings by, colloquially speaking, determining all the possible ways to walk through it from left to right while only descending into one branch of each alternation one comes across (see the right part of the diagram). When implementing it, one can of course combine the parsing and expansion into a single algorithm, but this specification discusses them separately for the sake of clarity. Expansion of alternations can be more rigorously described by these rules: a ⎧ ⎨ ⎩ 2 ⎫ ⎬ ⎭ 1 b ⎧ ⎨ ⎩ X ⎫ ⎬ ⎭ Y X c ⟶ a2bXc a2bYc a2bXc a1bXc a1bYc a1bXc An alternation causes the list of alternatives that will be produced by its parent branch to be increased 𝑛-fold, each copy featuring one of the 𝑛 alternatives produced by the alternation's child branches, in turn, at that position. This means that multiple alternations inside the same branch are cumulative  (i.e. the complete list of alternatives produced by a branch is the string-concatenating "Cartesian product" of its parts). All alternatives (even duplicate and empty ones) are preserved, and they are ordered like the examples demonstrate  (i.e. "lexicographically" with regard to the alternations). The alternatives produced by the root branch constitute the final output. Parsing the input string involves some additional complexity to deal with escaped characters and "incomplete" brace pairs: a\\{\\\{b,c\,d} ⟶ a\\ ⎧ ⎨ ⎩ \\\{b ⎫ ⎬ ⎭ c\,d {a,b{c{,{d}}e}f ⟶ {a,b{c ⎧ ⎨ ⎩ ‌ ⎫ ⎬ ⎭ {d} e}f An unescaped backslash which precedes another character, escapes that character (to force it to be treated as literal). The backslashes are passed along to the output unchanged. Balanced brace pairs are identified by, conceptually, going through the string from left to right and associating each unescaped closing brace that is encountered with the nearest still unassociated unescaped opening brace to its left (if any). Furthermore, each unescaped comma is associated with the innermost brace pair that contains it (if any). With that in mind: Each brace pair that has at least one comma associated with it, forms an alternation (whose branches are the brace pair's contents split at its commas). The associated brace and comma characters themselves do not become part of the output. Brace characters from pairs without any associated comma, as well as unassociated brace and comma characters, as well as all characters that are not covered by the preceding rules, are instead treated as literals. For every possible input string, your implementation should produce exactly the output which this specification mandates. Please comply with this even when it's inconvenient, to ensure that all implementations are comparable. However, none of the above should be interpreted as instructions (or even recommendations) for how to implement it. Try to come up with a solution that is idiomatic in your programming language. (See #Perl for a reference implementation.) Test Cases Input (single string) Ouput (list/array of strings) ~/{Downloads,Pictures}/*.{jpg,gif,png} ~/Downloads/*.jpg ~/Downloads/*.gif ~/Downloads/*.png ~/Pictures/*.jpg ~/Pictures/*.gif ~/Pictures/*.png It{{em,alic}iz,erat}e{d,}, please. Itemized, please. Itemize, please. Italicized, please. Italicize, please. Iterated, please. Iterate, please. {,{,gotta have{ ,\, again\, }}more }cowbell! cowbell! more cowbell! gotta have more cowbell! gotta have\, again\, more cowbell! {}} some }{,{\\{ edge, edge} \,}{ cases, {here} \\\\\} {}} some }{,{\\ edge \,}{ cases, {here} \\\\\} {}} some }{,{\\ edge \,}{ cases, {here} \\\\\} Other tasks related to string operations: Metrics Array length String length Copy a string Empty string  (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff  (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet   Brace_expansion_using_ranges
#Scheme
Scheme
  (define (parse-brackets str) ;; We parse the bracketed strings using an accumulator and a stack ;; ;; lst is the stream of tokens ;; acc is the accumulated list of "bits" in this branch ;; stk is a list of partially completed accumulators ;; (let go ((lst (string->list str)) (acc '()) (stk '())) (cond ((null? lst) (unless (null? stk) (error "parse-brackets" 'non-empty-stack)) (comma-sep acc)) ((eq? (car lst) #\{) (go (cdr lst) '() (cons acc stk))) ((eq? (car lst) #\}) (when (null? stk) (error "parse-brackets" 'empty-stack)) (go (cdr lst) (cons (comma-sep acc) (car stk)) (cdr stk))) (else (go (cdr lst) (cons (car lst) acc) stk)))))   (define (comma-sep lst) ;; This function is applied to the accumulator, it does three things: ;; - it reverses the list ;; - joins characters into short strings ;; - splits the strings based on commas ;; (let go ((lst lst) (acc '()) (rst '())) (if (null? lst) (cons (list->string acc) rst) (cond ((eq? #\, (car lst)) (go (cdr lst) '() (cons (list->string acc) rst))) ((char? (car lst)) (go (cdr lst) (cons (car lst) acc) rst)) (else (go (cdr lst) '() (cons (car lst) (cons (list->string acc) rst))))))))   ;; We use the list monad for the nondeterminism needed to expand out every possible bracket option   (define (concatenate lists) (apply append lists))   (define (return x) (list x)) (define (>>= l f) (concatenate (map f l)))   (define (sequence lsts) (if (null? lsts) (return '()) (>>= (car lsts) (lambda (option) (>>= (sequence (cdr lsts)) (lambda (tail) (return (cons option tail))))))))   (define (expand-inner tree) (if (string? tree) (return tree) (>>= tree (lambda (option) (expand-inner option)))))   (define (expand tree) (define (string-append* lst) (apply string-append lst)) (map string-append* (sequence (map expand-inner tree))))   (define (bracket-expand str) (expand (parse-brackets str)))   (bracket-expand "It{{em,alic}iz,erat}e{d,}") ;; '("Ited" "Ite" "Itemed" "Iteme" "Italiced" "Italice" "Itized" "Itize" "Iterated" "Iterate")  
http://rosettacode.org/wiki/Brazilian_numbers
Brazilian numbers
Brazilian numbers are so called as they were first formally presented at the 1994 math Olympiad Olimpiada Iberoamericana de Matematica in Fortaleza, Brazil. Brazilian numbers are defined as: The set of positive integer numbers where each number N has at least one natural number B where 1 < B < N-1 where the representation of N in base B has all equal digits. E.G. 1, 2 & 3 can not be Brazilian; there is no base B that satisfies the condition 1 < B < N-1. 4 is not Brazilian; 4 in base 2 is 100. The digits are not all the same. 5 is not Brazilian; 5 in base 2 is 101, in base 3 is 12. There is no representation where the digits are the same. 6 is not Brazilian; 6 in base 2 is 110, in base 3 is 20, in base 4 is 12. There is no representation where the digits are the same. 7 is Brazilian; 7 in base 2 is 111. There is at least one representation where the digits are all the same. 8 is Brazilian; 8 in base 3 is 22. There is at least one representation where the digits are all the same. and so on... All even integers 2P >= 8 are Brazilian because 2P = 2(P-1) + 2, which is 22 in base P-1 when P-1 > 2. That becomes true when P >= 4. More common: for all all integers R and S, where R > 1 and also S-1 > R, then R*S is Brazilian because R*S = R(S-1) + R, which is RR in base S-1 The only problematic numbers are squares of primes, where R = S. Only 11^2 is brazilian to base 3. All prime integers, that are brazilian, can only have the digit 1. Otherwise one could factor out the digit, therefore it cannot be a prime number. Mostly in form of 111 to base Integer(sqrt(prime number)). Must be an odd count of 1 to stay odd like primes > 2 Task Write a routine (function, whatever) to determine if a number is Brazilian and use the routine to show here, on this page; the first 20 Brazilian numbers; the first 20 odd Brazilian numbers; the first 20 prime Brazilian numbers; See also OEIS:A125134 - Brazilian numbers OEIS:A257521 - Odd Brazilian numbers OEIS:A085104 - Prime Brazilian numbers
#Nim
Nim
proc isPrime(n: Positive): bool = ## Check if a number is prime. if n mod 2 == 0: return n == 2 if n mod 3 == 0: return n == 3 var d = 5 while d * d <= n: if n mod d == 0: return false if n mod (d + 2) == 0: return false inc d, 6 result = true   proc sameDigits(n, b: Positive): bool = ## Check if the digits of "n" in base "b" are all the same. var d = n mod b var n = n div b if d == 0: return false while n > 0: if n mod b != d: return false n = n div b result = true   proc isBrazilian(n: Positive): bool = ## Check if a number is brazilian. if n < 7: return false if (n and 1) == 0: return true for b in 2..(n - 2): if sameDigits(n, b): return true   #———————————————————————————————————————————————————————————————————————————————————————————————————   when isMainModule: import strutils   template printList(title: string; findNextToCheck: untyped) = ## Template to print a list of brazilians numbers. ## "findNextTocheck" is a list of instructions to find the ## next candidate starting for the current one "n".   block: echo '\n' & title var n {.inject.} = 7 var list: seq[int] while true: if n.isBrazilian(): list.add(n) if list.len == 20: break findNextToCheck echo list.join(", ")     printList("First 20 Brazilian numbers:"): inc n   printList("First 20 odd Brazilian numbers:"): inc n, 2   printList("First 20 prime Brazilian numbers:"): inc n, 2 while not n.isPrime(): inc n, 2
http://rosettacode.org/wiki/Calendar
Calendar
Create a routine that will generate a text calendar for any year. Test the calendar by generating a calendar for the year 1969, on a device of the time. Choose one of the following devices: A line printer with a width of 132 characters. An IBM 3278 model 4 terminal (80×43 display with accented characters). Target formatting the months of the year to fit nicely across the 80 character width screen. Restrict number of lines in test output to 43. (Ideally, the program will generate well-formatted calendars for any page width from 20 characters up.) Kudos (κῦδος) for routines that also transition from Julian to Gregorian calendar. This task is inspired by Real Programmers Don't Use PASCAL by Ed Post, Datamation, volume 29 number 7, July 1983. THE REAL PROGRAMMER'S NATURAL HABITAT "Taped to the wall is a line-printer Snoopy calender for the year 1969." For further Kudos see task CALENDAR, where all code is to be in UPPERCASE. For economy of size, do not actually include Snoopy generation in either the code or the output, instead just output a place-holder. Related task   Five weekends
#Julia
Julia
  using Dates   const pagesizes = Dict( "lpr" => [132, 66], "tn3270" => [80, 43])   pagefit(prn) = haskey(pagesizes, prn) ? [div(pagesizes[prn][1], 22), div(pagesizes[prn][2], 12)] : [1, 1] pagecols(prn) = haskey(pagesizes, prn) ? pagesizes[prn][1] : 20   function centerobject(x, cols) content = string(x) rpad(lpad(content, div(cols + length(content), 2)), cols) end   function ljustlines(x, cols) arr = Vector{String}() for s in split(x, "\n") push!(arr, rpad(s, cols)[1:cols]) end join(arr, "\n") end   function formatmonth(yr, mo) dt = Date("$yr-$mo-01") dayofweekfirst = dayofweek(dt) numweeklines = 1 str = centerobject(monthname(dt), 20) * "\nMo Tu We Th Fr Sa Su\n" str *= " " ^ (3 * (dayofweekfirst - 1)) * lpad(string(1), 2) for i = 2:daysinmonth(dt) if (i + dayofweekfirst + 5) % 7 == 0 str *= "\n" * lpad(i, 2) numweeklines += 1 else str *= lpad(string(i), 3) end end str *= numweeklines < 6 ? "\n\n\n" : "\n\n" ljustlines(str, 20) end   function formatyear(displayyear, printertype) calmonths = [formatmonth(displayyear, mo) for mo in 1:12] columns = pagecols(printertype) monthsperline = pagefit(printertype)[1] joinspaces = max( (monthsperline > 1) ? div(columns - monthsperline * 20, monthsperline - 1) : 1, 1) str = "\n" * centerobject(displayyear, columns) * "\n" monthcal = [split(formatmonth(displayyear, i), "\n") for i in 1:12] for i in 1:monthsperline:length(calmonths) - 1 for j in 1:length(monthcal[1]) monthlines = map(x->monthcal[x][j], i:i + monthsperline - 1) str *= rpad(join(monthlines, " " ^ joinspaces), columns) * "\n" end str *= "\n" end str end   function lineprintcalendar(years) for year in years, printer in keys(pagesizes) println(formatyear(year, printer)) end end   lineprintcalendar(1969)  
http://rosettacode.org/wiki/Brownian_tree
Brownian tree
Brownian tree You are encouraged to solve this task according to the task description, using any language you may know. Task Generate and draw a   Brownian Tree. A Brownian Tree is generated as a result of an initial seed, followed by the interaction of two processes. The initial "seed" is placed somewhere within the field. Where is not particularly important; it could be randomized, or it could be a fixed point. Particles are injected into the field, and are individually given a (typically random) motion pattern. When a particle collides with the seed or tree, its position is fixed, and it's considered to be part of the tree. Because of the lax rules governing the random nature of the particle's placement and motion, no two resulting trees are really expected to be the same, or even necessarily have the same general shape.
#Octave
Octave
function r = browniantree(xsize, ysize = xsize, numparticle = 1000) r = zeros(xsize, ysize, "uint8"); r(unidrnd(xsize), unidrnd(ysize)) = 1;   for i = 1:numparticle px = unidrnd(xsize-1)+1; py = unidrnd(ysize-1)+1; while(1) dx = unidrnd(2) - 1; dy = unidrnd(2) - 1; if ( (dx+px < 1) || (dx+px > xsize) || (dy+py < 1) || (dy+py > ysize) ) px = unidrnd(xsize-1)+1; py = unidrnd(ysize-1)+1; elseif ( r(px+dx, py+dy) != 0 ) r(px, py) = 1; break; else px += dx; py += dy; endif endwhile endfor endfunction   r = browniantree(200); r( r > 0 ) = 255; jpgwrite("browniantree.jpg", r, 100); % image package
http://rosettacode.org/wiki/Bulls_and_cows
Bulls and cows
Bulls and Cows Task Create a four digit random number from the digits   1   to   9,   without duplication. The program should:   ask for guesses to this number   reject guesses that are malformed   print the score for the guess The score is computed as: The player wins if the guess is the same as the randomly chosen number, and the program ends. A score of one bull is accumulated for each digit in the guess that equals the corresponding digit in the randomly chosen initial number. A score of one cow is accumulated for each digit in the guess that also appears in the randomly chosen number, but in the wrong position. Related tasks   Bulls and cows/Player   Guess the number   Guess the number/With Feedback   Mastermind
#FOCAL
FOCAL
01.10 T %1,"BULLS AND COWS"!"----- --- ----"!! 01.20 S T=0;D 3 01.30 D 2;D 5;S T=T+1;T "BULLS",B," COWS",C,!! 01.40 I (B-4)1.3 01.50 T "YOU WON! GUESSES",%4,T,!! 01.60 Q   02.10 A "GUESS",A 02.20 F X=0,3;S B=FITR(A/10);S G(3-X)=A-B*10;S A=B 02.30 S A=1 02.40 F X=0,3;S A=A*G(X) 02.50 I (-A)2.6;T "NEED FOUR NONZERO DIGITS"!;G 2.1 02.60 F X=0,2;F Y=X+1,3;S A=A*(FABS(G(X)-G(Y))) 02.70 I (-A)2.8;T "NO DUPLICATES ALLOWED"!;G 2.1 02.80 R   03.10 F X=0,3;S S(X)=0 03.20 F X=0,3;D 4;S S(X)=A   04.10 S A=10*FRAN();S A=FITR(1+9*(A-FITR(A))) 04.20 S Z=1 04.30 F Y=0,3;S Z=Z*(FABS(A-S(Y))) 04.40 I (-Z)4.5,4.1 04.50 R   05.10 S B=0 05.20 F X=0,3;D 5.6 05.30 S C=-B 05.40 F X=0,3;F Y=0,3;D 5.7 05.50 R 05.60 I (-FABS(S(X)-G(X)))5.5,5.8 05.70 I (-FABS(S(X)-G(Y)))5.5,5.9 05.80 S B=B+1 05.90 S C=C+1
http://rosettacode.org/wiki/Caesar_cipher
Caesar cipher
Task Implement a Caesar cipher, both encoding and decoding. The key is an integer from 1 to 25. This cipher rotates (either towards left or right) the letters of the alphabet (A to Z). The encoding replaces each letter with the 1st to 25th next letter in the alphabet (wrapping Z to A). So key 2 encrypts "HI" to "JK", but key 20 encrypts "HI" to "BC". This simple "mono-alphabetic substitution cipher" provides almost no security, because an attacker who has the encoded message can either use frequency analysis to guess the key, or just try all 25 keys. Caesar cipher is identical to Vigenère cipher with a key of length 1. Also, Rot-13 is identical to Caesar cipher with key 13. Related tasks Rot-13 Substitution Cipher Vigenère Cipher/Cryptanalysis
#Dyalect
Dyalect
func Char.Encrypt(code) { if !this.IsLetter() { return this } var offset = (this.IsUpper() ? 'A' : 'a').Order() return Char((this.Order() + code - offset) % 26 + offset) }   func String.Encrypt(code) { var xs = [] for c in this { xs.Add(c.Encrypt(code)) } return String.Concat(values: xs) }   func String.Decrypt(code) { this.Encrypt(26 - code); }   var str = "Pack my box with five dozen liquor jugs." print(str) str = str.Encrypt(5) print("Encrypted: \(str)") str = str.Decrypt(5) print("Decrypted: \(str)")
http://rosettacode.org/wiki/Calculating_the_value_of_e
Calculating the value of e
Task Calculate the value of   e. (e   is also known as   Euler's number   and   Napier's constant.) See details: Calculating the value of e
#REXX
REXX
╔═══════════════════════════════════════════════════════════════════════════════════════╗ ║ ║ ║ 1 1 1 1 1 1 1 ║ ║ e = ─── + ─── + ─── + ─── + ─── + ─── + ─── + ∙∙∙ ║ ║ 0! 1! 2! 3! 4! 5! 6! ║ ║ ║ ╚═══════════════════════════════════════════════════════════════════════════════════════╝
http://rosettacode.org/wiki/Calculating_the_value_of_e
Calculating the value of e
Task Calculate the value of   e. (e   is also known as   Euler's number   and   Napier's constant.) See details: Calculating the value of e
#Ring
Ring
  # Project : Calculating the value of e   decimals(14)   for n = 1 to 100000 e = pow((1 + 1/n),n) next see "Calculating the value of e with method #1:" + nl see "e = " + e + nl   e = 0 for n = 0 to 12 e = e + (1 / factorial(n)) next see "Calculating the value of e with method #2:" + nl see "e = " + e + nl   func factorial(n) if n = 0 or n = 1 return 1 else return n * factorial(n-1) ok  
http://rosettacode.org/wiki/Bulls_and_cows/Player
Bulls and cows/Player
Task Write a player of the Bulls and Cows game, rather than a scorer. The player should give intermediate answers that respect the scores to previous attempts. One method is to generate a list of all possible numbers that could be the answer, then to prune the list by keeping only those numbers that would give an equivalent score to how your last guess was scored. Your next guess can be any number from the pruned list. Either you guess correctly or run out of numbers to guess, which indicates a problem with the scoring. Related tasks   Bulls and cows   Guess the number   Guess the number/With Feedback (Player)
#Tcl
Tcl
package require struct::list package require struct::set   proc scorecalc {guess chosen} { set bulls 0 set cows 0 foreach g $guess c $chosen { if {$g eq $c} { incr bulls } elseif {$g in $chosen} { incr cows } } return [list $bulls $cows] }   # Allow override on command line set size [expr {$argc ? int($argv) : 4}]   set choices {} struct::list foreachperm p [split 123456789 ""] { struct::set include choices [lrange $p 1 $size] } set answers {} set scores {}   puts "Playing Bulls & Cows with $size unique digits\n" fconfigure stdout -buffering none while 1 { set ans [lindex $choices [expr {int(rand()*[llength $choices])}]] lappend answers $ans puts -nonewline \ "Guess [llength $answers] is [join $ans {}]. Answer (Bulls, cows)? " set score [scan [gets stdin] %d,%d] lappend scores $score if {$score eq {$size 0}} { puts "Ye-haw!" break } foreach c $choices[set choices {}] { if {[scorecalc $c $ans] eq $score} { lappend choices $c } } if {![llength $choices]} { puts "Bad scoring? nothing fits those scores you gave:" foreach a $answers s $scores { puts " [join $a {}] -> ([lindex $s 0], [lindex $s 1])" } break } }
http://rosettacode.org/wiki/Call_a_function
Call a function
Task Demonstrate the different syntax and semantics provided for calling a function. This may include:   Calling a function that requires no arguments   Calling a function with a fixed number of arguments   Calling a function with optional arguments   Calling a function with a variable number of arguments   Calling a function with named arguments   Using a function in statement context   Using a function in first-class context within an expression   Obtaining the return value of a function   Distinguishing built-in functions and user-defined functions   Distinguishing subroutines and functions   Stating whether arguments are passed by value or by reference   Is partial application possible and how This task is not about defining functions.
#J
J
verb noun noun verb noun
http://rosettacode.org/wiki/Catalan_numbers
Catalan numbers
Catalan numbers You are encouraged to solve this task according to the task description, using any language you may know. Catalan numbers are a sequence of numbers which can be defined directly: C n = 1 n + 1 ( 2 n n ) = ( 2 n ) ! ( n + 1 ) ! n !  for  n ≥ 0. {\displaystyle C_{n}={\frac {1}{n+1}}{2n \choose n}={\frac {(2n)!}{(n+1)!\,n!}}\qquad {\mbox{ for }}n\geq 0.} Or recursively: C 0 = 1 and C n + 1 = ∑ i = 0 n C i C n − i for  n ≥ 0 ; {\displaystyle C_{0}=1\quad {\mbox{and}}\quad C_{n+1}=\sum _{i=0}^{n}C_{i}\,C_{n-i}\quad {\text{for }}n\geq 0;} Or alternatively (also recursive): C 0 = 1 and C n = 2 ( 2 n − 1 ) n + 1 C n − 1 , {\displaystyle C_{0}=1\quad {\mbox{and}}\quad C_{n}={\frac {2(2n-1)}{n+1}}C_{n-1},} Task Implement at least one of these algorithms and print out the first 15 Catalan numbers with each. Memoization   is not required, but may be worth the effort when using the second method above. Related tasks Catalan numbers/Pascal's triangle Evaluate binomial coefficients
#Nim
Nim
import math import strformat   proc catalan1(n: int): int = binom(2 * n, n) div (n + 1)   proc catalan2(n: int): int = if n == 0: return 1 for i in 0..<n: result += catalan2(i) * catalan2(n - 1 - i)   proc catalan3(n: int): int = if n > 0: 2 * (2 * n - 1) * catalan3(n - 1) div (1 + n) else: 1   for i in 0..15: echo &"{i:7} {catalan1(i):7} {catalan2(i):7} {catalan3(i):7}"
http://rosettacode.org/wiki/Brace_expansion
Brace expansion
Brace expansion is a type of parameter expansion made popular by Unix shells, where it allows users to specify multiple similar string parameters without having to type them all out. E.g. the parameter enable_{audio,video} would be interpreted as if both enable_audio and enable_video had been specified. Task[edit] Write a function that can perform brace expansion on any input string, according to the following specification. Demonstrate how it would be used, and that it passes the four test cases given below. Specification In the input string, balanced pairs of braces containing comma-separated substrings (details below) represent alternations that specify multiple alternatives which are to appear at that position in the output. In general, one can imagine the information conveyed by the input string as a tree of nested alternations interspersed with literal substrings, as shown in the middle part of the following diagram: It{{em,alic}iz,erat}e{d,} parse  ―――――▶ ‌ It ⎧ ⎨ ⎩ ⎧ ⎨ ⎩ em ⎫ ⎬ ⎭ alic iz ⎫ ⎬ ⎭ erat e ⎧ ⎨ ⎩ d ⎫ ⎬ ⎭ ‌ expand  ―――――▶ ‌ Itemized Itemize Italicized Italicize Iterated Iterate input string alternation tree output (list of strings) This tree can in turn be transformed into the intended list of output strings by, colloquially speaking, determining all the possible ways to walk through it from left to right while only descending into one branch of each alternation one comes across (see the right part of the diagram). When implementing it, one can of course combine the parsing and expansion into a single algorithm, but this specification discusses them separately for the sake of clarity. Expansion of alternations can be more rigorously described by these rules: a ⎧ ⎨ ⎩ 2 ⎫ ⎬ ⎭ 1 b ⎧ ⎨ ⎩ X ⎫ ⎬ ⎭ Y X c ⟶ a2bXc a2bYc a2bXc a1bXc a1bYc a1bXc An alternation causes the list of alternatives that will be produced by its parent branch to be increased 𝑛-fold, each copy featuring one of the 𝑛 alternatives produced by the alternation's child branches, in turn, at that position. This means that multiple alternations inside the same branch are cumulative  (i.e. the complete list of alternatives produced by a branch is the string-concatenating "Cartesian product" of its parts). All alternatives (even duplicate and empty ones) are preserved, and they are ordered like the examples demonstrate  (i.e. "lexicographically" with regard to the alternations). The alternatives produced by the root branch constitute the final output. Parsing the input string involves some additional complexity to deal with escaped characters and "incomplete" brace pairs: a\\{\\\{b,c\,d} ⟶ a\\ ⎧ ⎨ ⎩ \\\{b ⎫ ⎬ ⎭ c\,d {a,b{c{,{d}}e}f ⟶ {a,b{c ⎧ ⎨ ⎩ ‌ ⎫ ⎬ ⎭ {d} e}f An unescaped backslash which precedes another character, escapes that character (to force it to be treated as literal). The backslashes are passed along to the output unchanged. Balanced brace pairs are identified by, conceptually, going through the string from left to right and associating each unescaped closing brace that is encountered with the nearest still unassociated unescaped opening brace to its left (if any). Furthermore, each unescaped comma is associated with the innermost brace pair that contains it (if any). With that in mind: Each brace pair that has at least one comma associated with it, forms an alternation (whose branches are the brace pair's contents split at its commas). The associated brace and comma characters themselves do not become part of the output. Brace characters from pairs without any associated comma, as well as unassociated brace and comma characters, as well as all characters that are not covered by the preceding rules, are instead treated as literals. For every possible input string, your implementation should produce exactly the output which this specification mandates. Please comply with this even when it's inconvenient, to ensure that all implementations are comparable. However, none of the above should be interpreted as instructions (or even recommendations) for how to implement it. Try to come up with a solution that is idiomatic in your programming language. (See #Perl for a reference implementation.) Test Cases Input (single string) Ouput (list/array of strings) ~/{Downloads,Pictures}/*.{jpg,gif,png} ~/Downloads/*.jpg ~/Downloads/*.gif ~/Downloads/*.png ~/Pictures/*.jpg ~/Pictures/*.gif ~/Pictures/*.png It{{em,alic}iz,erat}e{d,}, please. Itemized, please. Itemize, please. Italicized, please. Italicize, please. Iterated, please. Iterate, please. {,{,gotta have{ ,\, again\, }}more }cowbell! cowbell! more cowbell! gotta have more cowbell! gotta have\, again\, more cowbell! {}} some }{,{\\{ edge, edge} \,}{ cases, {here} \\\\\} {}} some }{,{\\ edge \,}{ cases, {here} \\\\\} {}} some }{,{\\ edge \,}{ cases, {here} \\\\\} Other tasks related to string operations: Metrics Array length String length Copy a string Empty string  (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff  (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet   Brace_expansion_using_ranges
#Seed7
Seed7
$ include "seed7_05.s7i";   const proc: expandBraces (in string: stri) is func local var boolean: escaped is FALSE; var integer: depth is 0; var array integer: bracePoints is 0 times 0; var array integer: bracesToParse is 0 times 0; var string: prefix is ""; var string: suffix is ""; var string: option is ""; var integer: idx is 0; begin for key idx range stri do case stri[idx] of when {'\\'}: escaped := not escaped; when {'{'}: incr(depth); if not escaped and depth = 1 then bracePoints := [] (idx); end if; when {','}: if not escaped and depth = 1 then bracePoints &:= idx; end if; when {'}'}: if not escaped and depth = 1 and length(bracePoints) >= 2 then bracesToParse := bracePoints & [] (idx); end if; decr(depth); end case; if stri[idx] <> '\\' then escaped := FALSE; end if; end for; if length(bracesToParse) <> 0 then prefix := stri[.. pred(bracesToParse[1])]; suffix := stri[succ(bracesToParse[length(bracesToParse)]) ..]; for idx range 1 to pred(length(bracesToParse)) do option := stri[succ(bracesToParse[idx]) .. pred(bracesToParse[succ(idx)])]; expandBraces(prefix & option & suffix); end for; else writeln(stri); end if; end func;   const proc: main is func local var string: stri is ""; begin for stri range [] ("It{{em,alic}iz,erat}e{d,}, please.", "~/{Downloads,Pictures}/*.{jpg,gif,png}", "{,{,gotta have{ ,\\, again\\, }}more }cowbell!", "{}} some }{,{\\\\{ edge, edge} \\,}{ cases, {here} \\\\\\\\\\}") do writeln; expandBraces(stri); end for; end func;
http://rosettacode.org/wiki/Brazilian_numbers
Brazilian numbers
Brazilian numbers are so called as they were first formally presented at the 1994 math Olympiad Olimpiada Iberoamericana de Matematica in Fortaleza, Brazil. Brazilian numbers are defined as: The set of positive integer numbers where each number N has at least one natural number B where 1 < B < N-1 where the representation of N in base B has all equal digits. E.G. 1, 2 & 3 can not be Brazilian; there is no base B that satisfies the condition 1 < B < N-1. 4 is not Brazilian; 4 in base 2 is 100. The digits are not all the same. 5 is not Brazilian; 5 in base 2 is 101, in base 3 is 12. There is no representation where the digits are the same. 6 is not Brazilian; 6 in base 2 is 110, in base 3 is 20, in base 4 is 12. There is no representation where the digits are the same. 7 is Brazilian; 7 in base 2 is 111. There is at least one representation where the digits are all the same. 8 is Brazilian; 8 in base 3 is 22. There is at least one representation where the digits are all the same. and so on... All even integers 2P >= 8 are Brazilian because 2P = 2(P-1) + 2, which is 22 in base P-1 when P-1 > 2. That becomes true when P >= 4. More common: for all all integers R and S, where R > 1 and also S-1 > R, then R*S is Brazilian because R*S = R(S-1) + R, which is RR in base S-1 The only problematic numbers are squares of primes, where R = S. Only 11^2 is brazilian to base 3. All prime integers, that are brazilian, can only have the digit 1. Otherwise one could factor out the digit, therefore it cannot be a prime number. Mostly in form of 111 to base Integer(sqrt(prime number)). Must be an odd count of 1 to stay odd like primes > 2 Task Write a routine (function, whatever) to determine if a number is Brazilian and use the routine to show here, on this page; the first 20 Brazilian numbers; the first 20 odd Brazilian numbers; the first 20 prime Brazilian numbers; See also OEIS:A125134 - Brazilian numbers OEIS:A257521 - Odd Brazilian numbers OEIS:A085104 - Prime Brazilian numbers
#Pascal
Pascal
program brazilianNumbers;   {$IFDEF FPC} {$MODE DELPHI}{$OPTIMIZATION ON,All} {$CODEALIGN proc=32,loop=4} {$ELSE} {$APPTYPE CONSOLE} {$ENDIF} uses SysUtils;   const //Must not be a prime PrimeMarker = 0; SquareMarker = PrimeMarker + 1; //MAX = 110468;// 1E5 brazilian //MAX = 1084566;// 1E6 brazilian //MAX = 10708453;// 1E7 brazilian //MAX = 106091516;// 1E8 brazilian MAX = 1053421821;// 1E9 brazilian   var isprime: array of word;   procedure MarkSmallestFactor; //sieve of erathotenes //but saving the smallest factor var i, j, lmt: NativeUint; begin lmt := High(isPrime); fillWord(isPrime[0], lmt + 1, PrimeMarker); //mark even numbers i := 2; j := i * i; isPrime[j] := SquareMarker; Inc(j, 2); while j <= lmt do begin isPrime[j] := 2; Inc(j, 2); end; //mark 3 but not 2 i := 3; j := i * i; isPrime[j] := SquareMarker; Inc(j, 6); while j <= lmt do begin isPrime[j] := 3; Inc(j, 6); end;   i := 5; while i * i <= lmt do begin if isPrime[i] = 0 then begin j := lmt div i; if not (odd(j)) then Dec(j); while j > i do begin if isPrime[j] = 0 then isPrime[i * j] := i; Dec(j, 2); end; //mark square prime isPrime[i * i] := SquareMarker; end; Inc(i, 2); end; end;   procedure OutFactors(n: NativeUint); var divisor, Next, rest: NativeUint; pot: NativeUint; begin divisor := 2; Next := 3; rest := n; Write(n: 10, ' = '); while (rest <> 1) do begin if (rest mod divisor = 0) then begin Write(divisor); pot := 0; repeat rest := rest div divisor; Inc(pot) until rest mod divisor <> 0; if pot > 1 then Write('^', pot); if rest > 1 then Write('*'); end; divisor := Next; Next := Next + 2; // cut condition: avoid many useless iterations if (rest <> 1) and (rest < divisor * divisor) then begin Write(rest); rest := 1; end; end; Write(' ', #9#9#9); end;   procedure OutToBase(number, base: NativeUint); var BaseDgt: array[0..63] of NativeUint; i, rest: NativeINt; begin OutFactors(number); i := 0; while number <> 0 do begin rest := number div base; BaseDgt[i] := number - rest * base; number := rest; Inc(i); end; while i > 1 do begin Dec(i); Write(BaseDgt[i]); end; writeln(BaseDgt[0], ' to base ', base); end;   function PrimeBase(number: NativeUint): NativeUint; var lnN: extended; i, exponent, n: NativeUint; begin // primes are only brazilian if 111...11 to base > 2 // the count of "1" must be odd , because brazilian primes are odd lnN := ln(number); exponent := 4; //result := exponent.th root of number Result := trunc(exp(lnN*0.25)); while result >2 do Begin // calc sum(i= 0 to exponent ) base^i; n := Result + 1; i := 2; repeat Inc(i); n := n*result + 1; until i > exponent; if n = number then EXIT; Inc(exponent,2); Result := trunc(exp(lnN/exponent)); end; //not brazilian Result := 0; end;   function GetPrimeBrazilianBase(number: NativeUint): NativeUint; //result is base begin // prime of 2^n - 1 if (Number and (number + 1)) = 0 then Result := 2 else begin Result := trunc(sqrt(number)); //most of the brazilian primes are of this type base^2+base+1 IF (sqr(result)+result+1) <> number then result := PrimeBase(number); end; end;   function GetBrazilianBase(number: NativeUInt): NativeUint; inline; begin Result := isPrime[number]; if Result > SquareMarker then Result := (number div Result) - 1 else begin if Result = SquareMarker then begin if number = 121 then Result := 3 else Result := 0; end else Result := GetPrimeBrazilianBase(number); end; end;   procedure First20Brazilian; var i, n, cnt: NativeUInt; begin writeln('first 20 brazilian numbers'); i := 7; cnt := 0; while cnt < 20 do begin n := GetBrazilianBase(i); if n <> 0 then begin Inc(cnt); OutToBase(i, n); end; Inc(i); end; writeln; end;   procedure First33OddBrazilian; var i, n, cnt: NativeUInt; begin writeln('first 33 odd brazilian numbers'); i := 7; cnt := 0; while cnt < 33 do begin n := GetBrazilianBase(i); if N <> 0 then begin Inc(cnt); OutToBase(i, n); end; Inc(i, 2); end; writeln; end;   procedure First20BrazilianPrimes; var i, n, cnt: NativeUInt; begin writeln('first 20 brazilian prime numbers'); i := 7; cnt := 0; while cnt < 20 do begin IF isPrime[i] = PrimeMarker then Begin n := GetBrazilianBase(i); if n <> 0 then begin Inc(cnt); OutToBase(i, n); end; end; Inc(i); end; writeln; end;   var T1, T0: TDateTime; i, n, cnt, lmt: NativeUInt; begin lmt := MAX; setlength(isPrime, lmt + 1); MarkSmallestFactor;   First20Brazilian; First33OddBrazilian; First20BrazilianPrimes;   Write('count brazilian numbers up to ', lmt, ' = '); T0 := now; i := 7; cnt := 0; n := 0;   while (i <= lmt) do begin Inc(n, Ord(isPrime[i] = PrimeMarker)); if GetBrazilianBase(i) <> 0 then Inc(cnt); Inc(i); end;   T1 := now;   writeln(cnt); writeln('Count of primes ', n: 11+13); writeln((T1 - T0) * 86400 * 1000: 10: 0, ' ms');   setlength(isPrime, 0); end.
http://rosettacode.org/wiki/Calendar
Calendar
Create a routine that will generate a text calendar for any year. Test the calendar by generating a calendar for the year 1969, on a device of the time. Choose one of the following devices: A line printer with a width of 132 characters. An IBM 3278 model 4 terminal (80×43 display with accented characters). Target formatting the months of the year to fit nicely across the 80 character width screen. Restrict number of lines in test output to 43. (Ideally, the program will generate well-formatted calendars for any page width from 20 characters up.) Kudos (κῦδος) for routines that also transition from Julian to Gregorian calendar. This task is inspired by Real Programmers Don't Use PASCAL by Ed Post, Datamation, volume 29 number 7, July 1983. THE REAL PROGRAMMER'S NATURAL HABITAT "Taped to the wall is a line-printer Snoopy calender for the year 1969." For further Kudos see task CALENDAR, where all code is to be in UPPERCASE. For economy of size, do not actually include Snoopy generation in either the code or the output, instead just output a place-holder. Related task   Five weekends
#Kotlin
Kotlin
import java.io.PrintStream import java.text.DateFormatSymbols import java.text.MessageFormat import java.util.Calendar import java.util.GregorianCalendar import java.util.Locale   internal fun PrintStream.printCalendar(year: Int, nCols: Byte, locale: Locale?) { if (nCols < 1 || nCols > 12) throw IllegalArgumentException("Illegal column width.") val w = nCols * 24 val nRows = Math.ceil(12.0 / nCols).toInt()   val date = GregorianCalendar(year, 0, 1) var offs = date.get(Calendar.DAY_OF_WEEK) - 1   val days = DateFormatSymbols(locale).shortWeekdays.slice(1..7).map { it.slice(0..1) }.joinToString(" ", " ") val mons = Array(12) { Array(8) { "" } } DateFormatSymbols(locale).months.slice(0..11).forEachIndexed { m, name -> val len = 11 + name.length / 2 val format = MessageFormat.format("%{0}s%{1}s", len, 21 - len) mons[m][0] = String.format(format, name, "") mons[m][1] = days val dim = date.getActualMaximum(Calendar.DAY_OF_MONTH) for (d in 1..42) { val isDay = d > offs && d <= offs + dim val entry = if (isDay) String.format(" %2s", d - offs) else " " if (d % 7 == 1) mons[m][2 + (d - 1) / 7] = entry else mons[m][2 + (d - 1) / 7] += entry } offs = (offs + dim) % 7 date.add(Calendar.MONTH, 1) }   printf("%" + (w / 2 + 10) + "s%n", "[Snoopy Picture]") printf("%" + (w / 2 + 4) + "s%n%n", year)   for (r in 0 until nRows) { for (i in 0..7) { var c = r * nCols while (c < (r + 1) * nCols && c < 12) { printf("  %s", mons[c][i]) c++ } println() } println() } }   fun main(args: Array<String>) { System.out.printCalendar(1969, 3, Locale.US) }
http://rosettacode.org/wiki/Brownian_tree
Brownian tree
Brownian tree You are encouraged to solve this task according to the task description, using any language you may know. Task Generate and draw a   Brownian Tree. A Brownian Tree is generated as a result of an initial seed, followed by the interaction of two processes. The initial "seed" is placed somewhere within the field. Where is not particularly important; it could be randomized, or it could be a fixed point. Particles are injected into the field, and are individually given a (typically random) motion pattern. When a particle collides with the seed or tree, its position is fixed, and it's considered to be part of the tree. Because of the lax rules governing the random nature of the particle's placement and motion, no two resulting trees are really expected to be the same, or even necessarily have the same general shape.
#PARI.2FGP
PARI/GP
  \\ 2 old plotting helper functions 3/2/16 aev \\ insm(): Check if x,y are inside matrix mat (+/- p deep). insm(mat,x,y,p=0)={my(xz=#mat[1,],yz=#mat[,1]); return(x+p>0 && x+p<=xz && y+p>0 && y+p<=yz && x-p>0 && x-p<=xz && y-p>0 && y-p<=yz)} \\ plotmat(): Simple plotting using a square matrix mat (filled with 0/1). plotmat(mat)={ my(xz=#mat[1,],yz=#mat[,1],vx=List(),vy=vx,x,y); for(i=1,yz, for(j=1,xz, if(mat[i,j]==0, next, listput(vx,i); listput(vy,j)))); print(" *** matrix(",xz,"x",yz,") ",#vy, " DOTS"); plothraw(Vec(vx),Vec(vy)); } \\ 2 new plotting helper functions 11/27/16 aev \\ wrtmat(): Writing file fn containing X,Y coordinates from matrix mat. \\ Created primarily for using file in Gnuplot, also for re-plotting. wrtmat(mat, fn)={ my(xz=#mat[1,],yz=#mat[,1],ws,d=0); for(i=1,yz, for(j=1,xz, if(mat[i,j]==0, next, d++; ws=Str(i," ",j); write(fn,ws)))); print(" *** matrix(",xz,"x",yz,") ",d, " DOTS put in ",fn); } \\ plotff(): Plotting from a file written by the wrtmat(). \\ Saving possibly huge generation time if re-plotting needed. plotff(fn)={ my(F,nf,vx=List(),vy=vx,Vr); F=readstr(fn); nf=#F; print(" *** Plotting from: ", fn, " - ", nf, " DOTS"); for(i=1,nf, Vr=stok(F[i],","); listput(vx,eval(Vr[1])); listput(vy,eval(Vr[2]))); plothraw(Vec(vx),Vec(vy)); }  
http://rosettacode.org/wiki/Bulls_and_cows
Bulls and cows
Bulls and Cows Task Create a four digit random number from the digits   1   to   9,   without duplication. The program should:   ask for guesses to this number   reject guesses that are malformed   print the score for the guess The score is computed as: The player wins if the guess is the same as the randomly chosen number, and the program ends. A score of one bull is accumulated for each digit in the guess that equals the corresponding digit in the randomly chosen initial number. A score of one cow is accumulated for each digit in the guess that also appears in the randomly chosen number, but in the wrong position. Related tasks   Bulls and cows/Player   Guess the number   Guess the number/With Feedback   Mastermind
#Forth
Forth
include random.fs   create hidden 4 allot   : ok? ( str -- ? ) dup 4 <> if 2drop false exit then 1 9 lshift 1- -rot bounds do i c@ '1 - dup 0 9 within 0= if 2drop false leave then 1 swap lshift over and dup 0= if nip leave then xor loop 0<> ;   : init begin hidden 4 bounds do 9 random '1 + i c! loop hidden 4 ok? until ;   : check? ( addr -- solved? ) 0 4 0 do over i + c@ 4 0 do dup hidden i + c@ = if swap i j = if 8 else 1 then + swap then loop drop loop nip 8 /mod tuck . ." bulls, " . ." cows" 4 = ;   : guess: ( "1234" -- ) bl parse 2dup ok? 0= if 2drop ." Bad guess! (4 unique digits, 1-9)" exit then drop check? if cr ." You guessed it!" then ;
http://rosettacode.org/wiki/Caesar_cipher
Caesar cipher
Task Implement a Caesar cipher, both encoding and decoding. The key is an integer from 1 to 25. This cipher rotates (either towards left or right) the letters of the alphabet (A to Z). The encoding replaces each letter with the 1st to 25th next letter in the alphabet (wrapping Z to A). So key 2 encrypts "HI" to "JK", but key 20 encrypts "HI" to "BC". This simple "mono-alphabetic substitution cipher" provides almost no security, because an attacker who has the encoded message can either use frequency analysis to guess the key, or just try all 25 keys. Caesar cipher is identical to Vigenère cipher with a key of length 1. Also, Rot-13 is identical to Caesar cipher with key 13. Related tasks Rot-13 Substitution Cipher Vigenère Cipher/Cryptanalysis
#EDSAC_order_code
EDSAC order code
  [Caesar cipher for Rosetta Code. EDSAC program, Initial Orders 2.]   [Table for converting alphabetic position 0..25 to EDSAC code. The EDSAC code is in the high 5 bits.] T 54 K [access table via C parameter] P 56 F T 56 K AFBFCFDFEFFFGFHFIFJFKFLFMFNFOFPFQFRFSFTFUFVFWFXFYFZF   [Table for converting 5-bit EDSAC code to alphabetic position 0..25. Computed at run time (so the programmer doesn't need to know the EDSAC codes). 32 entries; entry is -1 if the EDSAC code does not represent a letter.] T 53 K [access table via B parameter] P 82 F   [Subroutine to read string from input and store with char codes in high 5 bits. String is terminated by blank row of tape, which is stored. Input: 0F holds address of string in address field (bits 1..11). 22 locations; workspace: 4D] T 114 K GKA3FT19@AFA20@T10@I5FA4DR16FT4DA4FUFE14@A21@G18@T5FA10@A2FE4@T5FEFUFK2048F   [Subroutine to print string with character codes in high 5 bits. String is terminated by blank row of tape, which is not printed. Input: 0F holds address of string in address field (bits 1..11). 18 locations; orkspace: 4F] T 136 K GKA3FT16@AFA2@T5@AFU4FE10@A17@G15@O4FT4FA5@A2FG4@TFEFK2048F   [Define start of user message] T 47 K [access message via M parameter] P 350 F [address of message]   T 154 K G K [Constants] [0] P M [address of user message] [1] A B [2] A C [3] T B [4] P 25 F [5] P 26 F [6] P 31 F [7] K 2048 F [(1) letter shift (2) used in test for blank row of tape at end of message] [8] @ F [carriage return] [9] & F [line feed] [10] K 4096 F [null char]   [Constant messages. Each includes new line at the end.] [11] TF EF SF TF IF NF GF @F &F K4096F [21] P 11 @ [22] EF NF TF EF RF !F MF EF SF SF AF GF EF @F &F K4096F [38] P 22 @ [39] MF UF SF TF !F SF TF AF RF TF !F WF IF TF HF !F BF !F TF OF !F ZF @F &F K4096F [64] P 39 @   [Subroutine to convert EDSAC code to alphabetic position. Input: 4F holds EDSAC code in high 5 bits Output: 4F holds alphabetic position (0..25, or -1 if not a letter). Workspace: 5F] [65] A 3 F [make jump for return] T 75 @ [plant in code] A 4 F [load EDSAC code] R 512 F [shift code into address field] T 5 F [temp store] C 5 F [acc := address bits only] A 1 @ [make order to load alphabetic position] T 73 @ [plant in code] [73] A B [load alphabetic position] T 4 F [store in 4F] [75] E F [return]   [Subroutine to encipher or decipher a message by Caesar shift. Input: Message is accessed by the M parameter, and terminated by a blank row of tape. Output: 0F = error flag: 0 if OK, < 0 if error (bad message prefix) Workspace 4F.] [76] A 3 F [make jump for return] T 119 @ [plant in code] A 80 @ [load order to access first char] T 95 @ [plant in code] [80] A M [load first char of message] T 4 F [pass to subroutine] [82] A 82 @ [get alphabetic position] G 65 @ A 4 F [load alphabetic position] U F [to 0F for use as shift] S 2 F [check it's not 0 or -1] G 118 @ [error exit if it is] T 1 F [clear acc] S F [load negative of shift] G 108 @ [jump to store first char and convert rest of message] [Here after skipping non-letter] [91] T 4 F [clear acc] [Here after converting letter] [92] A 95 @ [load order to read character] A 2 F [inc address to next character] T 95 @ [store back] [95] A M [load char from message (in top 5 bits)] E 100 @ [if >= 0 then not blank row] A 7 @ [if < 0, test for blank row] G 117 @ [jump out if so] S 7 @ [restore after test] [100] T 4 F [character to 4F for subroutine] [101] A 101 @ [for return from subroutine] G 65 @ [sets 4F := alphabetic position] A 4 F [to acc] G 91 @ [if < 0 then not a letter; don't change it] A F [apply Caesar shift] [Subtract 26 if required, so result is in range 0..25] S 5 @ [subtract 26] E 109 @ [skip next if result >= 0] [108] A 5 @ [add 26] [109] A 2 @ [make order to read EDSAC letter at that position] T 114 @ [plant in code] A 95 @ [load A order from above] A 14 C [add 'O F' to make T order] T 115 @ [plant in code] [114] A C [load enciphered letter] [115] T M [overwrite original letter] E 92 @ [loop back] [117] T F [flag = 0 for OK] [118] T F [flag to 0F: 0 if OK, < 0 if error] [119] E F [return with acc = 0]   [Subroutine to print encipered or deciphered message, plus new line] [120] A 3 F [make jump order for return] T 128 @ [plant in code] A @ [load address of message] T F [to 0F for print subroutine] [124] A 124 @ G 136 F [print message, clears acc] O 8 @ [print new line] O 9 @ [128] E F [return with acc = 0]   [Main routine] [129] O 7 @ [set letter shift] H 6 @ [mult reg has this value throughout; selects bits 1..5 of 17-bit value] [Build inverse table from direct table First initialize all 32 locations to -1] A 6 @ [work backwards] [132] A 3 @ [make T order for inverse table] T 135 @ [plant in code] S 2 F [make -1 in address field] [135] T B [store in inverse table] A 135 @ [get T order] S 2 F [dec address] S 3 @ [compare with start of table] E 132 @ [loop till done] [Now fill in entries by reversing direct table] T F [clear acc] A 4 @ [work backwards] [142] U 5 F [index in 5F] A 2 @ [make A order for direct table] T 145 @ [plant in code] [145] A C [load entry from direct table, code in top 5 bits] R 512 F [shift 11 right, 5-bit code to address field] T 4 F [temp store] C 4 F [pick out 5-bit code] A 3 @ [make T order for inverse table] T 152 @ [plant in code] A 5 F [load index] [152] T B [store in inverse table] A 5 F [load index again] S 2 F [update index] E 142 @ [loop back] [Here when inverse table is complete] [156] T F [clear acc] [157] A 21 @ [load address of "testing" message] T F [to 0F for print subroutine] [159] A 159 @ G 136 F [print "testing message"] E 168 @ [jump to read from end of this file] [Loop back here to get message from user] [162] A 38 @ [load address of prompt] T F [to 0F for print subroutine] [164] A 164 @ G 136 F [print prompt] O 10 @ [print null to flush teleprinter buffer] Z F [stop] [First time here, read message from end of this file. Later times, read message from file chosen by the user.] [168] A @ [load address of message] T F [to 0F for input] [170] A 170 @ G 114 F [read message] [172] A 172 @ G 120 @ [print message] [174] A 174 @ G 76 @ [call Caesar shift subroutine] A F [load error flag] E 184 @ [jump if OK] T F [error, clear acc] A 64 @ [load address of error message] T F [181] A 181 @ G 136 F [print error message] E 162 @ [back to try again] [Here if message was enciphered without error] [184] A 184 @ G 120 @ [print enciphered message] [186] A 186 @ G 76 @ [call Caesar shift subroutine] [188] A 188 @ G 120 @ [print deciphered message] E 162 @ [back for another message] E 129 Z [define entry point] P F [acc = 0 on entry] DGAZA!FREQUENS!LIBYCUM!DUXIT!KARTHAGO!TRIUMPHUM.  
http://rosettacode.org/wiki/Calculating_the_value_of_e
Calculating the value of e
Task Calculate the value of   e. (e   is also known as   Euler's number   and   Napier's constant.) See details: Calculating the value of e
#Ruby
Ruby
  fact = 1 e = 2 e0 = 0 n = 2   until (e - e0).abs < Float::EPSILON do e0 = e fact *= n n += 1 e += 1.0 / fact end   puts e  
http://rosettacode.org/wiki/Bulls_and_cows/Player
Bulls and cows/Player
Task Write a player of the Bulls and Cows game, rather than a scorer. The player should give intermediate answers that respect the scores to previous attempts. One method is to generate a list of all possible numbers that could be the answer, then to prune the list by keeping only those numbers that would give an equivalent score to how your last guess was scored. Your next guess can be any number from the pruned list. Either you guess correctly or run out of numbers to guess, which indicates a problem with the scoring. Related tasks   Bulls and cows   Guess the number   Guess the number/With Feedback (Player)
#VBA
VBA
  Option Explicit   Sub Main_Bulls_And_Cows_Player() Dim collSoluces As New Collection, Elem As Variant, Soluce As String Dim strNumber As String, cpt As Byte, p As Byte Dim i As Byte, Bulls() As Boolean, NbBulls As Byte, Cows As Byte, Poss As Long Const NUMBER_OF_DIGITS As Byte = 4   strNumber = CreateNb(NUMBER_OF_DIGITS) Debug.Print "TOSS : " & StrConv(strNumber, vbUnicode) Debug.Print "---------- START ------------" Set collSoluces = CollOfPossibleNumbers Poss = collSoluces.Count For Each Elem In collSoluces 'Debug.Print "Number of possibilities : " & Poss Debug.Print "Attempt : " & StrConv(Elem, vbUnicode) NbBulls = 0: Soluce = Elem ReDim Bulls(NUMBER_OF_DIGITS - 1) For i = 1 To NUMBER_OF_DIGITS If IsBull(strNumber, Mid(Elem, i, 1), i) Then Bulls(i - 1) = True: NbBulls = NbBulls + 1 RemoveIfNotBull collSoluces, Mid(Elem, i, 1), i End If Next i Cows = 0 For i = 1 To NUMBER_OF_DIGITS If Not Bulls(i - 1) Then If IsCow(collSoluces, strNumber, Mid(Elem, i, 1), p) Then If Not Bulls(p - 1) Then Cows = Cows + 1 End If End If Next i Poss = collSoluces.Count Debug.Print "Bulls : " & NbBulls & ", Cows : " & Cows If Poss = 1 Then Exit For Next Debug.Print "---------- THE END ------------" Debug.Print "TOSS WAS : " & StrConv(strNumber, vbUnicode) & " We found : " & StrConv(Soluce, vbUnicode) End Sub   Function CreateNb(NbDigits As Byte) As String Dim myColl As New Collection Dim strTemp As String Dim bytAlea As Byte   Randomize Do bytAlea = Int((Rnd * 9) + 1) On Error Resume Next myColl.Add CStr(bytAlea), CStr(bytAlea) If Err <> 0 Then On Error GoTo 0 Else strTemp = strTemp & CStr(bytAlea) End If Loop While Len(strTemp) < NbDigits CreateNb = strTemp End Function   Function CollOfPossibleNumbers() As Collection Dim TempColl As New Collection Dim x As String Dim i As Long Dim Flag As Boolean Dim b As Byte   For i = 1234 To 9876 Flag = False For b = 1 To 4 x = CStr(i) If Len(Replace(x, Mid(x, b, 1), "")) < 3 Then Flag = True: Exit For End If Next If Not Flag Then TempColl.Add x, x Next i Set CollOfPossibleNumbers = TempColl End Function   Function IsBull(strgNb As String, Digit As String, place As Byte) As Boolean IsBull = (Mid(strgNb, place, 1) = Digit) End Function   Function IsCow(C As Collection, strgNb As String, Digit As String, place As Byte) As Boolean If (InStr(strgNb, Digit) > 0) Then IsCow = True: place = InStr(strgNb, Digit) RemoveIfNotCow C, Digit End If End Function   Sub RemoveIfNotBull(C As Collection, Digit As String, place As Byte) Dim E As Variant   For Each E In C If Mid(E, place, 1) <> Digit Then C.Remove E Next End Sub   Sub RemoveIfNotCow(C As Collection, Digit As String) Dim E As Variant   For Each E In C If (InStr(E, Digit) = 0) Then C.Remove E Next End Sub  
http://rosettacode.org/wiki/Call_a_function
Call a function
Task Demonstrate the different syntax and semantics provided for calling a function. This may include:   Calling a function that requires no arguments   Calling a function with a fixed number of arguments   Calling a function with optional arguments   Calling a function with a variable number of arguments   Calling a function with named arguments   Using a function in statement context   Using a function in first-class context within an expression   Obtaining the return value of a function   Distinguishing built-in functions and user-defined functions   Distinguishing subroutines and functions   Stating whether arguments are passed by value or by reference   Is partial application possible and how This task is not about defining functions.
#Java
Java
myMethod()
http://rosettacode.org/wiki/Catalan_numbers
Catalan numbers
Catalan numbers You are encouraged to solve this task according to the task description, using any language you may know. Catalan numbers are a sequence of numbers which can be defined directly: C n = 1 n + 1 ( 2 n n ) = ( 2 n ) ! ( n + 1 ) ! n !  for  n ≥ 0. {\displaystyle C_{n}={\frac {1}{n+1}}{2n \choose n}={\frac {(2n)!}{(n+1)!\,n!}}\qquad {\mbox{ for }}n\geq 0.} Or recursively: C 0 = 1 and C n + 1 = ∑ i = 0 n C i C n − i for  n ≥ 0 ; {\displaystyle C_{0}=1\quad {\mbox{and}}\quad C_{n+1}=\sum _{i=0}^{n}C_{i}\,C_{n-i}\quad {\text{for }}n\geq 0;} Or alternatively (also recursive): C 0 = 1 and C n = 2 ( 2 n − 1 ) n + 1 C n − 1 , {\displaystyle C_{0}=1\quad {\mbox{and}}\quad C_{n}={\frac {2(2n-1)}{n+1}}C_{n-1},} Task Implement at least one of these algorithms and print out the first 15 Catalan numbers with each. Memoization   is not required, but may be worth the effort when using the second method above. Related tasks Catalan numbers/Pascal's triangle Evaluate binomial coefficients
#OCaml
OCaml
let imp_catalan n = let return = ref 1 in for i = 1 to n do return := !return * 2 * (2 * i - 1) / (i + 1) done; !return   let rec catalan = function | 0 -> 1 | n -> catalan (n - 1) * 2 * (2 * n - 1) / (n + 1)   let memoize f = let cache = Hashtbl.create 20 in fun n -> match Hashtbl.find_opt cache n with | None -> let x = f n in Hashtbl.replace cache n x; x | Some x -> x   let catalan_cache = Hashtbl.create 20   let rec memo_catalan n = if n = 0 then 1 else match Hashtbl.find_opt catalan_cache n with | None -> let x = memo_catalan (n - 1) * 2 * (2 * n - 1) / (n + 1) in Hashtbl.replace catalan_cache n x; x | Some x -> x   let () = if not !Sys.interactive then let bench label f n times = let start = Unix.gettimeofday () in begin for i = 1 to times do f n done; let stop = Unix.gettimeofday () in Printf.printf "%s (%d runs) : %.3f\n" label times (stop -. start) end in let show f g h f' n = for i = 0 to n do Printf.printf "%2d %7d %7d %7d %7d\n" i (f i) (g i) (h i) (f' i) done in List.iter (fun (l, f) -> bench l f 15 10_000_000) ["imperative", imp_catalan; "recursive", catalan; "hand-memoized", memo_catalan; "memoized", (memoize catalan)]; show imp_catalan catalan memo_catalan (memoize catalan) 15  
http://rosettacode.org/wiki/Brace_expansion
Brace expansion
Brace expansion is a type of parameter expansion made popular by Unix shells, where it allows users to specify multiple similar string parameters without having to type them all out. E.g. the parameter enable_{audio,video} would be interpreted as if both enable_audio and enable_video had been specified. Task[edit] Write a function that can perform brace expansion on any input string, according to the following specification. Demonstrate how it would be used, and that it passes the four test cases given below. Specification In the input string, balanced pairs of braces containing comma-separated substrings (details below) represent alternations that specify multiple alternatives which are to appear at that position in the output. In general, one can imagine the information conveyed by the input string as a tree of nested alternations interspersed with literal substrings, as shown in the middle part of the following diagram: It{{em,alic}iz,erat}e{d,} parse  ―――――▶ ‌ It ⎧ ⎨ ⎩ ⎧ ⎨ ⎩ em ⎫ ⎬ ⎭ alic iz ⎫ ⎬ ⎭ erat e ⎧ ⎨ ⎩ d ⎫ ⎬ ⎭ ‌ expand  ―――――▶ ‌ Itemized Itemize Italicized Italicize Iterated Iterate input string alternation tree output (list of strings) This tree can in turn be transformed into the intended list of output strings by, colloquially speaking, determining all the possible ways to walk through it from left to right while only descending into one branch of each alternation one comes across (see the right part of the diagram). When implementing it, one can of course combine the parsing and expansion into a single algorithm, but this specification discusses them separately for the sake of clarity. Expansion of alternations can be more rigorously described by these rules: a ⎧ ⎨ ⎩ 2 ⎫ ⎬ ⎭ 1 b ⎧ ⎨ ⎩ X ⎫ ⎬ ⎭ Y X c ⟶ a2bXc a2bYc a2bXc a1bXc a1bYc a1bXc An alternation causes the list of alternatives that will be produced by its parent branch to be increased 𝑛-fold, each copy featuring one of the 𝑛 alternatives produced by the alternation's child branches, in turn, at that position. This means that multiple alternations inside the same branch are cumulative  (i.e. the complete list of alternatives produced by a branch is the string-concatenating "Cartesian product" of its parts). All alternatives (even duplicate and empty ones) are preserved, and they are ordered like the examples demonstrate  (i.e. "lexicographically" with regard to the alternations). The alternatives produced by the root branch constitute the final output. Parsing the input string involves some additional complexity to deal with escaped characters and "incomplete" brace pairs: a\\{\\\{b,c\,d} ⟶ a\\ ⎧ ⎨ ⎩ \\\{b ⎫ ⎬ ⎭ c\,d {a,b{c{,{d}}e}f ⟶ {a,b{c ⎧ ⎨ ⎩ ‌ ⎫ ⎬ ⎭ {d} e}f An unescaped backslash which precedes another character, escapes that character (to force it to be treated as literal). The backslashes are passed along to the output unchanged. Balanced brace pairs are identified by, conceptually, going through the string from left to right and associating each unescaped closing brace that is encountered with the nearest still unassociated unescaped opening brace to its left (if any). Furthermore, each unescaped comma is associated with the innermost brace pair that contains it (if any). With that in mind: Each brace pair that has at least one comma associated with it, forms an alternation (whose branches are the brace pair's contents split at its commas). The associated brace and comma characters themselves do not become part of the output. Brace characters from pairs without any associated comma, as well as unassociated brace and comma characters, as well as all characters that are not covered by the preceding rules, are instead treated as literals. For every possible input string, your implementation should produce exactly the output which this specification mandates. Please comply with this even when it's inconvenient, to ensure that all implementations are comparable. However, none of the above should be interpreted as instructions (or even recommendations) for how to implement it. Try to come up with a solution that is idiomatic in your programming language. (See #Perl for a reference implementation.) Test Cases Input (single string) Ouput (list/array of strings) ~/{Downloads,Pictures}/*.{jpg,gif,png} ~/Downloads/*.jpg ~/Downloads/*.gif ~/Downloads/*.png ~/Pictures/*.jpg ~/Pictures/*.gif ~/Pictures/*.png It{{em,alic}iz,erat}e{d,}, please. Itemized, please. Itemize, please. Italicized, please. Italicize, please. Iterated, please. Iterate, please. {,{,gotta have{ ,\, again\, }}more }cowbell! cowbell! more cowbell! gotta have more cowbell! gotta have\, again\, more cowbell! {}} some }{,{\\{ edge, edge} \,}{ cases, {here} \\\\\} {}} some }{,{\\ edge \,}{ cases, {here} \\\\\} {}} some }{,{\\ edge \,}{ cases, {here} \\\\\} Other tasks related to string operations: Metrics Array length String length Copy a string Empty string  (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff  (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet   Brace_expansion_using_ranges
#Sidef
Sidef
func brace_expand (input) { var current = [''] var stack = [[current]]   loop { var t = input.match( /\G ((?:[^\\{,}]++ | \\(?:.|\z))++ | . )/gx )[0] \\ break   if (t == '{') { stack << [current = ['']] } elsif ((t == ',') && (stack.len > 1)) { stack[-1] << (current = ['']) } elsif ((t == '}') && (stack.len > 1)) { var group = stack.pop current = stack[-1][-1]   # handle the case of brace pairs without commas: group[0][] = group[0].map{ '{'+_+'}' }... if (group.len == 1)   current[] = current.map { |c| group.map { .map { c + _ }... }... }... } else { current[] = current.map { _ + t }... } }   # handle the case of missing closing braces: while (stack.len > 1) {   var right = stack[-1].pop var sep = ','   if (stack[-1].is_empty) { sep = '{' stack.pop }   current = stack[-1][-1] current[] = current.map { |c| right.map { c + sep + _ }... }... }   return current }   DATA.each { |line| say line brace_expand(line).each { "\t#{_}".say } say '' }   __DATA__ ~/{Downloads,Pictures}/*.{jpg,gif,png} It{{em,alic}iz,erat}e{d,}, please. {,{,gotta have{ ,\, again\, }}more }cowbell! {}} some }{,{\\{ edge, edge} \,}{ cases, {here} \\\\\}
http://rosettacode.org/wiki/Brazilian_numbers
Brazilian numbers
Brazilian numbers are so called as they were first formally presented at the 1994 math Olympiad Olimpiada Iberoamericana de Matematica in Fortaleza, Brazil. Brazilian numbers are defined as: The set of positive integer numbers where each number N has at least one natural number B where 1 < B < N-1 where the representation of N in base B has all equal digits. E.G. 1, 2 & 3 can not be Brazilian; there is no base B that satisfies the condition 1 < B < N-1. 4 is not Brazilian; 4 in base 2 is 100. The digits are not all the same. 5 is not Brazilian; 5 in base 2 is 101, in base 3 is 12. There is no representation where the digits are the same. 6 is not Brazilian; 6 in base 2 is 110, in base 3 is 20, in base 4 is 12. There is no representation where the digits are the same. 7 is Brazilian; 7 in base 2 is 111. There is at least one representation where the digits are all the same. 8 is Brazilian; 8 in base 3 is 22. There is at least one representation where the digits are all the same. and so on... All even integers 2P >= 8 are Brazilian because 2P = 2(P-1) + 2, which is 22 in base P-1 when P-1 > 2. That becomes true when P >= 4. More common: for all all integers R and S, where R > 1 and also S-1 > R, then R*S is Brazilian because R*S = R(S-1) + R, which is RR in base S-1 The only problematic numbers are squares of primes, where R = S. Only 11^2 is brazilian to base 3. All prime integers, that are brazilian, can only have the digit 1. Otherwise one could factor out the digit, therefore it cannot be a prime number. Mostly in form of 111 to base Integer(sqrt(prime number)). Must be an odd count of 1 to stay odd like primes > 2 Task Write a routine (function, whatever) to determine if a number is Brazilian and use the routine to show here, on this page; the first 20 Brazilian numbers; the first 20 odd Brazilian numbers; the first 20 prime Brazilian numbers; See also OEIS:A125134 - Brazilian numbers OEIS:A257521 - Odd Brazilian numbers OEIS:A085104 - Prime Brazilian numbers
#Perl
Perl
use strict; use warnings; use ntheory qw<is_prime>; use constant Inf => 1e10;   sub is_Brazilian { my($n) = @_; return 1 if $n > 6 && 0 == $n%2; LOOP: for (my $base = 2; $base < $n - 1; ++$base) { my $digit; my $nn = $n; while (1) { my $x = $nn % $base; $digit //= $x; next LOOP if $digit != $x; $nn = int $nn / $base; if ($nn < $base) { return 1 if $digit == $nn; next LOOP; } } } }   my $upto = 20;   print "First $upto Brazilian numbers:\n"; my $n = 0; print do { $n < $upto ? (is_Brazilian($_) and ++$n and "$_ ") : last } for 1 .. Inf;   print "\n\nFirst $upto odd Brazilian numbers:\n"; $n = 0; print do { $n < $upto ? (!!($_%2) and is_Brazilian($_) and ++$n and "$_ ") : last } for 1 .. Inf;   print "\n\nFirst $upto prime Brazilian numbers:\n"; $n = 0; print do { $n < $upto ? (!!is_prime($_) and is_Brazilian($_) and ++$n and "$_ ") : last } for 1 .. Inf;
http://rosettacode.org/wiki/Calendar
Calendar
Create a routine that will generate a text calendar for any year. Test the calendar by generating a calendar for the year 1969, on a device of the time. Choose one of the following devices: A line printer with a width of 132 characters. An IBM 3278 model 4 terminal (80×43 display with accented characters). Target formatting the months of the year to fit nicely across the 80 character width screen. Restrict number of lines in test output to 43. (Ideally, the program will generate well-formatted calendars for any page width from 20 characters up.) Kudos (κῦδος) for routines that also transition from Julian to Gregorian calendar. This task is inspired by Real Programmers Don't Use PASCAL by Ed Post, Datamation, volume 29 number 7, July 1983. THE REAL PROGRAMMER'S NATURAL HABITAT "Taped to the wall is a line-printer Snoopy calender for the year 1969." For further Kudos see task CALENDAR, where all code is to be in UPPERCASE. For economy of size, do not actually include Snoopy generation in either the code or the output, instead just output a place-holder. Related task   Five weekends
#Liberty_BASIC
Liberty BASIC
  rem Adapted from LB examples included with software [start] prompt "Enter year(yyyy)?";year if year<1900 then notice "1900 or later":goto [start] ax=1:gx=8:ay=3:gy=10 locate 52,1:print year for mr = 0 to 3 for mc = 0 to 2 mt=mt+1 aDate$ = str$(mt)+"/01/"+str$(year) px = ax+mc*gx py = ay+mr*gy gosub [printout] next mc next mr gosub [snoopy] end   [printout] locate 4*px-3+int((30-len(monthname$(aDate$)))/2),py print monthname$(aDate$) FirstDay=date$(word$(aDate$,1,"/")+"/1/"+word$(aDate$,3,"/")) LastDay$=date$(date$(word$(date$(FirstDay+32),1,"/")+"/1/"+word$(date$(FirstDay+32),3,"/"))-1) dow=val(word$("3 4 5 x 6 7 x 1 2",int((FirstDay/7-int(FirstDay/7))*10)+1)) locate px*4-3, py+1 print " Su Mo Tu We Th Fr Sa" for i=1 to val(mid$(LastDay$,4,2)) y=int((i+dow-2)/7) x=px+(i+dow-2)-y*7 x=4*x locate x-4,py+y+2 print using("###",i) next i return   [snoopy] locate ax, ay+4*gy print space$(4*gx);" ,-~~-.___." print space$(4*gx);" / ()=(() \" print space$(4*gx);" ( ( 0" print space$(4*gx);" \._\, ,----'" print space$(4*gx);" ##XXXxxxxxxx" print space$(4*gx);" / ---'~;" print space$(4*gx);" / /~|-" print space$(4*gx);" _____=( ~~ |______ " print space$(4*gx);" /_____________________\ " print space$(4*gx);" /_______________________\" print space$(4*gx);" /_________________________\" print space$(4*gx);"/___________________________\" print space$(4*gx);" |____________________|" print space$(4*gx);" |____________________|" print space$(4*gx);" |____________________|" print space$(4*gx);" | |" return   function monthname$(aDate$) month=val(aDate$) monthname$=word$("January February March April May June July August September October November December",month) end function  
http://rosettacode.org/wiki/Brownian_tree
Brownian tree
Brownian tree You are encouraged to solve this task according to the task description, using any language you may know. Task Generate and draw a   Brownian Tree. A Brownian Tree is generated as a result of an initial seed, followed by the interaction of two processes. The initial "seed" is placed somewhere within the field. Where is not particularly important; it could be randomized, or it could be a fixed point. Particles are injected into the field, and are individually given a (typically random) motion pattern. When a particle collides with the seed or tree, its position is fixed, and it's considered to be part of the tree. Because of the lax rules governing the random nature of the particle's placement and motion, no two resulting trees are really expected to be the same, or even necessarily have the same general shape.
#Perl
Perl
sub PI() { atan2(1,1) * 4 } # The, er, pi sub STEP() { .5 } # How far does the particle move each step. Affects # both speed and accuracy greatly sub STOP_RADIUS() { 100 } # When the tree reaches this far from center, end   # At each step, move this much towards center. Bigger numbers help the speed because # particles are less likely to wander off, but greatly affects tree shape. # Should be between 0 and 1 ish. Set to 0 for pain. sub ATTRACT() { .2 }   my @particles = map([ map([], 0 .. 2 * STOP_RADIUS) ], 0 .. 2 * STOP_RADIUS); push @{ $particles[STOP_RADIUS][STOP_RADIUS] }, [0, 0];   my $r_start = 3; my $max_dist = 0;   sub dist2 { my ($dx, $dy) = ($_[0][0] - $_[1][0], $_[0][1] - $_[1][1]); $dx * $dx + $dy * $dy }   sub move { my $p = shift; # moved too far, kill particle # return if dist2($p, [0, 0]) > 2 * $r_start * $r_start; $p->[0] += 2 * $r_start while $p->[0] < -$r_start; $p->[0] -= 2 * $r_start while $p->[0] > $r_start; $p->[1] += 2 * $r_start while $p->[1] < -$r_start; $p->[1] -= 2 * $r_start while $p->[1] > $r_start;   my ($ix, $iy) = (int($p->[0]), int($p->[1])); my $dist = 2 * $r_start * $r_start; my $nearest;   # see if the particle is close enough to stick to an exist one for ($ix - 1 .. $ix + 1) { my $idx = STOP_RADIUS + $_; next if $idx > 2 * STOP_RADIUS || $idx < 0; my $xs = $particles[ $idx ]; for ($iy - 1 .. $iy + 1) { my $idx = STOP_RADIUS + $_; next if $idx > 2 * STOP_RADIUS || $idx < 0; for (@{ $xs->[ $idx ] }) { my $d = dist2($p, $_); next if $d > 2; next if $d > $dist;   $dist = $d; $nearest = $_; } } }   # yes, found one if ($nearest) { my $displace = [ $p->[0] - $nearest->[0], $p->[1] - $nearest->[1] ]; my $angle = atan2($displace->[1], $displace->[0]); $p->[0] = $nearest->[0] + cos($angle); $p->[1] = $nearest->[1] + sin($angle);   push @{$particles[$ix + STOP_RADIUS][$iy + STOP_RADIUS]}, [ @$p ]; $dist = sqrt dist2($p);   if ($dist + 10 > $r_start && $r_start < STOP_RADIUS + 10) { $r_start = $dist + 10 } if (int($dist + 1) > $max_dist) { $max_dist = int($dist + 1); # write_eps(); # system('pstopnm -portrait -xborder 0 -yborder 0 test.eps 2> /dev/null'); # system('pnmtopng test.eps001.ppm 2>/dev/null > test.png'); return 3 if $max_dist >= STOP_RADIUS; } return 2; }   # random walk my $angle = rand(2 * PI); $p->[0] += STEP * cos($angle); $p->[1] += STEP * sin($angle);   # drag particle towards center by some distance my $nudge; if (sqrt(dist2($p, [0, 0])) > STOP_RADIUS + 1) { $nudge = 1; } else { $nudge = STEP * ATTRACT; }   if ($nudge) { $angle = atan2($p->[1], $p->[0]); $p->[0] -= $nudge * cos($angle); $p->[1] -= $nudge * sin($angle); }   return 1; }   my $count; PARTICLE: while (1) { my $a = rand(2 * PI); my $p = [ $r_start * cos($a), $r_start * sin($a) ]; while (my $m = move($p)) { if ($m == 1) { next } elsif ($m == 2) { $count++; last; } elsif ($m == 3) { last PARTICLE } else { last } } print STDERR "$count $max_dist/@{[int($r_start)]}/@{[STOP_RADIUS]}\r" unless $count% 7; }   sub write_eps { my $size = 128; my $p = $size / (STOP_RADIUS * 1.05); my $b = STOP_RADIUS * $p; if ($p < 1) { $size = STOP_RADIUS * 1.05; $b = STOP_RADIUS; $p = 1; }   my $hp = $p / 2;   open OUT, ">", "test.eps";   # print EPS to standard out print OUT <<"HEAD"; %!PS-Adobe-3.0 EPSF-3.0 %%BoundingBox: 0 0 @{[$size*2, $size*2]} $size $size translate /l{ rlineto }def /c{ $hp 0 360 arc fill }def -$size -$size moveto $size 2 mul 0 l 0 $size 2 mul l -$size 2 mul 0 l closepath 0 setgray fill 0 setlinewidth .1 setgray 0 0 $b 0 360 arc stroke .8 setgray /TimesRoman findfont 16 scalefont setfont -$size 10 add $size -16 add moveto (Step = @{[STEP]} Attract = @{[ATTRACT]}) show 0 1 0 setrgbcolor newpath HEAD   for (@particles) { for (@$_) { printf OUT "%.3g %.3g c ", map { $_ * $p } @$_ for @$_; } } print OUT "\n%%EOF"; close OUT; }   write_eps;
http://rosettacode.org/wiki/Bulls_and_cows
Bulls and cows
Bulls and Cows Task Create a four digit random number from the digits   1   to   9,   without duplication. The program should:   ask for guesses to this number   reject guesses that are malformed   print the score for the guess The score is computed as: The player wins if the guess is the same as the randomly chosen number, and the program ends. A score of one bull is accumulated for each digit in the guess that equals the corresponding digit in the randomly chosen initial number. A score of one cow is accumulated for each digit in the guess that also appears in the randomly chosen number, but in the wrong position. Related tasks   Bulls and cows/Player   Guess the number   Guess the number/With Feedback   Mastermind
#Fortran
Fortran
module bac implicit none   contains   subroutine Gennum(n) integer, intent(out) :: n(4) integer :: i, j real :: r   call random_number(r) n(1) = int(r * 9.0) + 1 i = 2   outer: do while (i <= 4) call random_number(r) n(i) = int(r * 9.0) + 1 inner: do j = i-1 , 1, -1 if (n(j) == n(i)) cycle outer end do inner i = i + 1 end do outer   end subroutine Gennum   subroutine Score(n, guess, b, c) character(*), intent(in) :: guess integer, intent(in) :: n(0:3) integer, intent(out) :: b, c integer :: digit, i, j, ind   b = 0; c = 0 do i = 1, 4 read(guess(i:i), "(i1)") digit if (digit == n(i-1)) then b = b + 1 else do j = i, i+2 ind = mod(j, 4) if (digit == n(ind)) then c = c + 1 exit end if end do end if end do   end subroutine Score   end module bac   program Bulls_and_Cows use bac implicit none   integer :: n(4) integer :: bulls=0, cows=0, tries=0 character(4) :: guess   call random_seed call Gennum(n)   write(*,*) "I have selected a number made up of 4 digits (1-9) without repetitions." write(*,*) "You attempt to guess this number." write(*,*) "Every digit in your guess that is in the correct position scores 1 Bull" write(*,*) "Every digit in your guess that is in an incorrect position scores 1 Cow" write(*,*)   do while (bulls /= 4) write(*,*) "Enter a 4 digit number" read*, guess if (verify(guess, "123456789") /= 0) then write(*,*) "That is an invalid entry. Please try again." cycle end if tries = tries + 1 call Score (n, guess, bulls, cows) write(*, "(a, i1, a, i1, a)") "You scored ", bulls, " bulls and ", cows, " cows" write(*,*) end do   write(*,"(a,i0,a)") "Congratulations! You correctly guessed the correct number in ", tries, " attempts"   end program Bulls_and_Cows
http://rosettacode.org/wiki/Caesar_cipher
Caesar cipher
Task Implement a Caesar cipher, both encoding and decoding. The key is an integer from 1 to 25. This cipher rotates (either towards left or right) the letters of the alphabet (A to Z). The encoding replaces each letter with the 1st to 25th next letter in the alphabet (wrapping Z to A). So key 2 encrypts "HI" to "JK", but key 20 encrypts "HI" to "BC". This simple "mono-alphabetic substitution cipher" provides almost no security, because an attacker who has the encoded message can either use frequency analysis to guess the key, or just try all 25 keys. Caesar cipher is identical to Vigenère cipher with a key of length 1. Also, Rot-13 is identical to Caesar cipher with key 13. Related tasks Rot-13 Substitution Cipher Vigenère Cipher/Cryptanalysis
#Eiffel
Eiffel
  class APPLICATION   inherit ARGUMENTS   create make   feature {NONE} -- Initialization   make -- Run application. local s: STRING_32 do s := "The tiny tiger totally taunted the tall Till." print ("%NString to encode: " + s) print ("%NEncoded string: " + encode (s, 12)) print ("%NDecoded string (after encoding and decoding): " + decode (encode (s, 12), 12)) end   feature -- Basic operations   decode (to_be_decoded: STRING_32; offset: INTEGER): STRING_32 -- Decode `to be decoded' according to `offset'. do Result := encode (to_be_decoded, 26 - offset) end   encode (to_be_encoded: STRING_32; offset: INTEGER): STRING_32 -- Encode `to be encoded' according to `offset'. local l_offset: INTEGER l_char_code: INTEGER do create Result.make_empty l_offset := (offset \\ 26) + 26 across to_be_encoded as tbe loop if tbe.item.is_alpha then if tbe.item.is_upper then l_char_code := ('A').code + (tbe.item.code - ('A').code + l_offset) \\ 26 Result.append_character (l_char_code.to_character_32) else l_char_code := ('a').code + (tbe.item.code - ('a').code + l_offset) \\ 26 Result.append_character (l_char_code.to_character_32) end else Result.append_character (tbe.item) end end end end  
http://rosettacode.org/wiki/Calculating_the_value_of_e
Calculating the value of e
Task Calculate the value of   e. (e   is also known as   Euler's number   and   Napier's constant.) See details: Calculating the value of e
#Rust
Rust
const EPSILON: f64 = 1e-15;   fn main() { let mut fact: u64 = 1; let mut e: f64 = 2.0; let mut n: u64 = 2; loop { let e0 = e; fact *= n; n += 1; e += 1.0 / fact as f64; if (e - e0).abs() < EPSILON { break; } } println!("e = {:.15}", e); }
http://rosettacode.org/wiki/Calculating_the_value_of_e
Calculating the value of e
Task Calculate the value of   e. (e   is also known as   Euler's number   and   Napier's constant.) See details: Calculating the value of e
#Scala
Scala
import scala.annotation.tailrec   object CalculateE extends App { private val ε = 1.0e-15   @tailrec def iter(fact: Long, ℯ: Double, n: Int, e0: Double): Double = { val newFact = fact * n val newE = ℯ + 1.0 / newFact if (math.abs(newE - ℯ) < ε) ℯ else iter(newFact, newE, n + 1, ℯ) }   println(f"ℯ = ${iter(1L, 2.0, 2, 0)}%.15f") }
http://rosettacode.org/wiki/Bulls_and_cows/Player
Bulls and cows/Player
Task Write a player of the Bulls and Cows game, rather than a scorer. The player should give intermediate answers that respect the scores to previous attempts. One method is to generate a list of all possible numbers that could be the answer, then to prune the list by keeping only those numbers that would give an equivalent score to how your last guess was scored. Your next guess can be any number from the pruned list. Either you guess correctly or run out of numbers to guess, which indicates a problem with the scoring. Related tasks   Bulls and cows   Guess the number   Guess the number/With Feedback (Player)
#Wren
Wren
import "random" for Random   var countBullsAndCows = Fn.new { |guess, answer| var bulls = 0 var cows = 0 var i = 0 for (d in guess) { if (answer[i] == d) { bulls = bulls + 1 } else if (answer.contains(d)) { cows = cows + 1 } i = i + 1 } return [bulls, cows] }   var r = Random.new() var choices = [] // generate all possible distinct 4 digit (1 to 9) integer arrays for (i in 1..9) { for (j in 1..9) { if (j != i) { for (k in 1..9) { if (k != i && k != j) { for (l in 1..9) { if (l != i && l != j && l != k) { choices.add([i, j, k, l]) } } } } } } }   // pick one at random as the answer var answer = choices[r.int(choices.count)]   // keep guessing, pruning the list as we go based on the score, until answer found while (true) { var guess = choices[r.int(choices.count)] var bc = countBullsAndCows.call(guess, answer) System.print("Guess = %(guess.join("")) Bulls = %(bc[0]) Cows = %(bc[1])") if (bc[0] == 4) { System.print("You've just found the answer!") return } for (i in choices.count - 1..0) { var bc2 = countBullsAndCows.call(choices[i], answer) // if score is no better remove it from the list of choices if (bc2[0] <= bc[0] && bc2[1] <= bc[1]) choices.removeAt(i) } if (choices.count == 0) { System.print("Something went wrong as no choices left! Aborting program") } }
http://rosettacode.org/wiki/Call_a_function
Call a function
Task Demonstrate the different syntax and semantics provided for calling a function. This may include:   Calling a function that requires no arguments   Calling a function with a fixed number of arguments   Calling a function with optional arguments   Calling a function with a variable number of arguments   Calling a function with named arguments   Using a function in statement context   Using a function in first-class context within an expression   Obtaining the return value of a function   Distinguishing built-in functions and user-defined functions   Distinguishing subroutines and functions   Stating whether arguments are passed by value or by reference   Is partial application possible and how This task is not about defining functions.
#JavaScript
JavaScript
var foo = function() { return arguments.length }; foo() // 0 foo(1, 2, 3) // 3
http://rosettacode.org/wiki/Catalan_numbers
Catalan numbers
Catalan numbers You are encouraged to solve this task according to the task description, using any language you may know. Catalan numbers are a sequence of numbers which can be defined directly: C n = 1 n + 1 ( 2 n n ) = ( 2 n ) ! ( n + 1 ) ! n !  for  n ≥ 0. {\displaystyle C_{n}={\frac {1}{n+1}}{2n \choose n}={\frac {(2n)!}{(n+1)!\,n!}}\qquad {\mbox{ for }}n\geq 0.} Or recursively: C 0 = 1 and C n + 1 = ∑ i = 0 n C i C n − i for  n ≥ 0 ; {\displaystyle C_{0}=1\quad {\mbox{and}}\quad C_{n+1}=\sum _{i=0}^{n}C_{i}\,C_{n-i}\quad {\text{for }}n\geq 0;} Or alternatively (also recursive): C 0 = 1 and C n = 2 ( 2 n − 1 ) n + 1 C n − 1 , {\displaystyle C_{0}=1\quad {\mbox{and}}\quad C_{n}={\frac {2(2n-1)}{n+1}}C_{n-1},} Task Implement at least one of these algorithms and print out the first 15 Catalan numbers with each. Memoization   is not required, but may be worth the effort when using the second method above. Related tasks Catalan numbers/Pascal's triangle Evaluate binomial coefficients
#Oforth
Oforth
: catalan( n -- m ) n ifZero: [ 1 ] else: [ catalan( n 1- ) 2 n * 1- * 2 * n 1+ / ] ;
http://rosettacode.org/wiki/Brace_expansion
Brace expansion
Brace expansion is a type of parameter expansion made popular by Unix shells, where it allows users to specify multiple similar string parameters without having to type them all out. E.g. the parameter enable_{audio,video} would be interpreted as if both enable_audio and enable_video had been specified. Task[edit] Write a function that can perform brace expansion on any input string, according to the following specification. Demonstrate how it would be used, and that it passes the four test cases given below. Specification In the input string, balanced pairs of braces containing comma-separated substrings (details below) represent alternations that specify multiple alternatives which are to appear at that position in the output. In general, one can imagine the information conveyed by the input string as a tree of nested alternations interspersed with literal substrings, as shown in the middle part of the following diagram: It{{em,alic}iz,erat}e{d,} parse  ―――――▶ ‌ It ⎧ ⎨ ⎩ ⎧ ⎨ ⎩ em ⎫ ⎬ ⎭ alic iz ⎫ ⎬ ⎭ erat e ⎧ ⎨ ⎩ d ⎫ ⎬ ⎭ ‌ expand  ―――――▶ ‌ Itemized Itemize Italicized Italicize Iterated Iterate input string alternation tree output (list of strings) This tree can in turn be transformed into the intended list of output strings by, colloquially speaking, determining all the possible ways to walk through it from left to right while only descending into one branch of each alternation one comes across (see the right part of the diagram). When implementing it, one can of course combine the parsing and expansion into a single algorithm, but this specification discusses them separately for the sake of clarity. Expansion of alternations can be more rigorously described by these rules: a ⎧ ⎨ ⎩ 2 ⎫ ⎬ ⎭ 1 b ⎧ ⎨ ⎩ X ⎫ ⎬ ⎭ Y X c ⟶ a2bXc a2bYc a2bXc a1bXc a1bYc a1bXc An alternation causes the list of alternatives that will be produced by its parent branch to be increased 𝑛-fold, each copy featuring one of the 𝑛 alternatives produced by the alternation's child branches, in turn, at that position. This means that multiple alternations inside the same branch are cumulative  (i.e. the complete list of alternatives produced by a branch is the string-concatenating "Cartesian product" of its parts). All alternatives (even duplicate and empty ones) are preserved, and they are ordered like the examples demonstrate  (i.e. "lexicographically" with regard to the alternations). The alternatives produced by the root branch constitute the final output. Parsing the input string involves some additional complexity to deal with escaped characters and "incomplete" brace pairs: a\\{\\\{b,c\,d} ⟶ a\\ ⎧ ⎨ ⎩ \\\{b ⎫ ⎬ ⎭ c\,d {a,b{c{,{d}}e}f ⟶ {a,b{c ⎧ ⎨ ⎩ ‌ ⎫ ⎬ ⎭ {d} e}f An unescaped backslash which precedes another character, escapes that character (to force it to be treated as literal). The backslashes are passed along to the output unchanged. Balanced brace pairs are identified by, conceptually, going through the string from left to right and associating each unescaped closing brace that is encountered with the nearest still unassociated unescaped opening brace to its left (if any). Furthermore, each unescaped comma is associated with the innermost brace pair that contains it (if any). With that in mind: Each brace pair that has at least one comma associated with it, forms an alternation (whose branches are the brace pair's contents split at its commas). The associated brace and comma characters themselves do not become part of the output. Brace characters from pairs without any associated comma, as well as unassociated brace and comma characters, as well as all characters that are not covered by the preceding rules, are instead treated as literals. For every possible input string, your implementation should produce exactly the output which this specification mandates. Please comply with this even when it's inconvenient, to ensure that all implementations are comparable. However, none of the above should be interpreted as instructions (or even recommendations) for how to implement it. Try to come up with a solution that is idiomatic in your programming language. (See #Perl for a reference implementation.) Test Cases Input (single string) Ouput (list/array of strings) ~/{Downloads,Pictures}/*.{jpg,gif,png} ~/Downloads/*.jpg ~/Downloads/*.gif ~/Downloads/*.png ~/Pictures/*.jpg ~/Pictures/*.gif ~/Pictures/*.png It{{em,alic}iz,erat}e{d,}, please. Itemized, please. Itemize, please. Italicized, please. Italicize, please. Iterated, please. Iterate, please. {,{,gotta have{ ,\, again\, }}more }cowbell! cowbell! more cowbell! gotta have more cowbell! gotta have\, again\, more cowbell! {}} some }{,{\\{ edge, edge} \,}{ cases, {here} \\\\\} {}} some }{,{\\ edge \,}{ cases, {here} \\\\\} {}} some }{,{\\ edge \,}{ cases, {here} \\\\\} Other tasks related to string operations: Metrics Array length String length Copy a string Empty string  (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff  (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet   Brace_expansion_using_ranges
#Simula
Simula
CLASS ARRAYLISTS; BEGIN   CLASS ITEM;;   CLASS ITEMARRAY(N); INTEGER N; BEGIN REF(ITEM) ARRAY DATA(1:N);  ! OUTTEXT("NEW ITEMARRAY WITH ");!OUTINT(N, 0);!OUTTEXT(" ELEMENTS");  ! OUTIMAGE; END;   CLASS ARRAYLIST; BEGIN   PROCEDURE EXPAND(N); INTEGER N; BEGIN INTEGER I; REF(ITEMARRAY) TEMP;  ! OUTTEXT("EXPAND TO CAPACITY ");!OUTINT(N, 0);!OUTIMAGE; TEMP :- NEW ITEMARRAY(N); FOR I := 1 STEP 1 UNTIL SIZE DO TEMP.DATA(I) :- ITEMS.DATA(I); ITEMS :- TEMP; END;   PROCEDURE ADD(T); REF(ITEM) T; BEGIN IF SIZE + 1 > CAPACITY THEN BEGIN CAPACITY := 2 * CAPACITY; EXPAND(CAPACITY); END; SIZE := SIZE + 1; ITEMS.DATA(SIZE) :- T;  ! OUTTEXT("SIZE IS ");!OUTINT(SIZE, 0);!OUTIMAGE; END;   PROCEDURE REMOVE(I); INTEGER I; BEGIN INTEGER J; IF I < 1 OR I > SIZE THEN ERROR("REMOVE: INDEX OUT OF BOUNDS"); FOR J := I STEP 1 UNTIL SIZE - 1 DO ITEMS.DATA(J) :- ITEMS.DATA(J + 1); ITEMS.DATA(SIZE) :- NONE; SIZE := SIZE - 1; END;   REF(ITEM) PROCEDURE GET(I); INTEGER I; BEGIN IF I < 1 OR I > SIZE THEN ERROR("GET: INDEX OUT OF BOUNDS"); GET :- ITEMS.DATA(I); END;   INTEGER CAPACITY; INTEGER SIZE; REF(ITEMARRAY) ITEMS;   CAPACITY := 20; SIZE := 0; EXPAND(CAPACITY);   END;     ITEM CLASS TEXTITEM(TXT); TEXT TXT;;   ARRAYLIST CLASS TEXTARRAYLIST; BEGIN PROCEDURE ADD(T); TEXT T; THIS TEXTARRAYLIST QUA ARRAYLIST.ADD(NEW TEXTITEM(T)); TEXT PROCEDURE GET(I); INTEGER I; GET :- THIS TEXTARRAYLIST QUA ARRAYLIST.GET(I) QUA TEXTITEM.TXT; END;     ITEM CLASS REALITEM(X); REAL X;;   ARRAYLIST CLASS REALARRAYLIST; BEGIN PROCEDURE ADD(X); REAL X; THIS REALARRAYLIST QUA ARRAYLIST.ADD(NEW REALITEM(X)); REAL PROCEDURE GET(I); INTEGER I; GET := THIS REALARRAYLIST QUA ARRAYLIST.GET(I) QUA REALITEM.X; END;   END;
http://rosettacode.org/wiki/Brace_expansion
Brace expansion
Brace expansion is a type of parameter expansion made popular by Unix shells, where it allows users to specify multiple similar string parameters without having to type them all out. E.g. the parameter enable_{audio,video} would be interpreted as if both enable_audio and enable_video had been specified. Task[edit] Write a function that can perform brace expansion on any input string, according to the following specification. Demonstrate how it would be used, and that it passes the four test cases given below. Specification In the input string, balanced pairs of braces containing comma-separated substrings (details below) represent alternations that specify multiple alternatives which are to appear at that position in the output. In general, one can imagine the information conveyed by the input string as a tree of nested alternations interspersed with literal substrings, as shown in the middle part of the following diagram: It{{em,alic}iz,erat}e{d,} parse  ―――――▶ ‌ It ⎧ ⎨ ⎩ ⎧ ⎨ ⎩ em ⎫ ⎬ ⎭ alic iz ⎫ ⎬ ⎭ erat e ⎧ ⎨ ⎩ d ⎫ ⎬ ⎭ ‌ expand  ―――――▶ ‌ Itemized Itemize Italicized Italicize Iterated Iterate input string alternation tree output (list of strings) This tree can in turn be transformed into the intended list of output strings by, colloquially speaking, determining all the possible ways to walk through it from left to right while only descending into one branch of each alternation one comes across (see the right part of the diagram). When implementing it, one can of course combine the parsing and expansion into a single algorithm, but this specification discusses them separately for the sake of clarity. Expansion of alternations can be more rigorously described by these rules: a ⎧ ⎨ ⎩ 2 ⎫ ⎬ ⎭ 1 b ⎧ ⎨ ⎩ X ⎫ ⎬ ⎭ Y X c ⟶ a2bXc a2bYc a2bXc a1bXc a1bYc a1bXc An alternation causes the list of alternatives that will be produced by its parent branch to be increased 𝑛-fold, each copy featuring one of the 𝑛 alternatives produced by the alternation's child branches, in turn, at that position. This means that multiple alternations inside the same branch are cumulative  (i.e. the complete list of alternatives produced by a branch is the string-concatenating "Cartesian product" of its parts). All alternatives (even duplicate and empty ones) are preserved, and they are ordered like the examples demonstrate  (i.e. "lexicographically" with regard to the alternations). The alternatives produced by the root branch constitute the final output. Parsing the input string involves some additional complexity to deal with escaped characters and "incomplete" brace pairs: a\\{\\\{b,c\,d} ⟶ a\\ ⎧ ⎨ ⎩ \\\{b ⎫ ⎬ ⎭ c\,d {a,b{c{,{d}}e}f ⟶ {a,b{c ⎧ ⎨ ⎩ ‌ ⎫ ⎬ ⎭ {d} e}f An unescaped backslash which precedes another character, escapes that character (to force it to be treated as literal). The backslashes are passed along to the output unchanged. Balanced brace pairs are identified by, conceptually, going through the string from left to right and associating each unescaped closing brace that is encountered with the nearest still unassociated unescaped opening brace to its left (if any). Furthermore, each unescaped comma is associated with the innermost brace pair that contains it (if any). With that in mind: Each brace pair that has at least one comma associated with it, forms an alternation (whose branches are the brace pair's contents split at its commas). The associated brace and comma characters themselves do not become part of the output. Brace characters from pairs without any associated comma, as well as unassociated brace and comma characters, as well as all characters that are not covered by the preceding rules, are instead treated as literals. For every possible input string, your implementation should produce exactly the output which this specification mandates. Please comply with this even when it's inconvenient, to ensure that all implementations are comparable. However, none of the above should be interpreted as instructions (or even recommendations) for how to implement it. Try to come up with a solution that is idiomatic in your programming language. (See #Perl for a reference implementation.) Test Cases Input (single string) Ouput (list/array of strings) ~/{Downloads,Pictures}/*.{jpg,gif,png} ~/Downloads/*.jpg ~/Downloads/*.gif ~/Downloads/*.png ~/Pictures/*.jpg ~/Pictures/*.gif ~/Pictures/*.png It{{em,alic}iz,erat}e{d,}, please. Itemized, please. Itemize, please. Italicized, please. Italicize, please. Iterated, please. Iterate, please. {,{,gotta have{ ,\, again\, }}more }cowbell! cowbell! more cowbell! gotta have more cowbell! gotta have\, again\, more cowbell! {}} some }{,{\\{ edge, edge} \,}{ cases, {here} \\\\\} {}} some }{,{\\ edge \,}{ cases, {here} \\\\\} {}} some }{,{\\ edge \,}{ cases, {here} \\\\\} Other tasks related to string operations: Metrics Array length String length Copy a string Empty string  (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff  (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet   Brace_expansion_using_ranges
#Tailspin
Tailspin
  templates braceExpansion composer braceParse [ <part|'[{}\\,]'>* ] // This is not simply <production> because there may be unbalanced special chars rule production: [ <part>* ] rule part: <alternation|balancedBraces|escapedCharacter|'[^{}\\,]+'>+ rule alternation: (<='{'>) [ <production> <alternate>+ ] (<='}'>) rule alternate: (<=','>) <production> rule balancedBraces: <='{'> <part>* <='}'> rule escapedCharacter: <'\\.'> end braceParse   templates collateSequence @: ['']; $... -> # $@! when <'.*'> do def part: $; @: [$@... -> '$;$part;']; otherwise def alternates: [ $... -> collateSequence ... ]; @: [$@... -> \(def prefix: $; $alternates... -> '$prefix;$;' ! \)]; end collateSequence   $ -> braceParse -> collateSequence ! end braceExpansion   '~/{Downloads,Pictures}/*.{jpg,gif,png}' -> '"$;" expands to:$ -> braceExpansion ... -> '$#10;$;';$#10;$#10;' -> !OUT::write   'It{{em,alic}iz,erat}e{d,}, please.' -> '"$;" expands to $ -> braceExpansion ... -> '$#10;$;';$#10;$#10;' -> !OUT::write   '{,{,gotta have{ ,\, again\, }}more }cowbell!' -> '"$;" expands to $ -> braceExpansion ... -> '$#10;$;';$#10;$#10;' -> !OUT::write   '{}} some }{,{\\{ edge, edge} \,}{ cases, {here} \\\\\}' -> '"$;" expands to $ -> braceExpansion ... -> '$#10;$;';$#10;$#10;' -> !OUT::write  
http://rosettacode.org/wiki/Brazilian_numbers
Brazilian numbers
Brazilian numbers are so called as they were first formally presented at the 1994 math Olympiad Olimpiada Iberoamericana de Matematica in Fortaleza, Brazil. Brazilian numbers are defined as: The set of positive integer numbers where each number N has at least one natural number B where 1 < B < N-1 where the representation of N in base B has all equal digits. E.G. 1, 2 & 3 can not be Brazilian; there is no base B that satisfies the condition 1 < B < N-1. 4 is not Brazilian; 4 in base 2 is 100. The digits are not all the same. 5 is not Brazilian; 5 in base 2 is 101, in base 3 is 12. There is no representation where the digits are the same. 6 is not Brazilian; 6 in base 2 is 110, in base 3 is 20, in base 4 is 12. There is no representation where the digits are the same. 7 is Brazilian; 7 in base 2 is 111. There is at least one representation where the digits are all the same. 8 is Brazilian; 8 in base 3 is 22. There is at least one representation where the digits are all the same. and so on... All even integers 2P >= 8 are Brazilian because 2P = 2(P-1) + 2, which is 22 in base P-1 when P-1 > 2. That becomes true when P >= 4. More common: for all all integers R and S, where R > 1 and also S-1 > R, then R*S is Brazilian because R*S = R(S-1) + R, which is RR in base S-1 The only problematic numbers are squares of primes, where R = S. Only 11^2 is brazilian to base 3. All prime integers, that are brazilian, can only have the digit 1. Otherwise one could factor out the digit, therefore it cannot be a prime number. Mostly in form of 111 to base Integer(sqrt(prime number)). Must be an odd count of 1 to stay odd like primes > 2 Task Write a routine (function, whatever) to determine if a number is Brazilian and use the routine to show here, on this page; the first 20 Brazilian numbers; the first 20 odd Brazilian numbers; the first 20 prime Brazilian numbers; See also OEIS:A125134 - Brazilian numbers OEIS:A257521 - Odd Brazilian numbers OEIS:A085104 - Prime Brazilian numbers
#Phix
Phix
with javascript_semantics function same_digits(integer n, b) integer f = remainder(n,b) n = floor(n/b) while n>0 do if remainder(n,b)!=f then return false end if n = floor(n/b) end while return true end function function is_brazilian(integer n) if n>=7 then if remainder(n,2)=0 then return true end if for b=2 to n-2 do if same_digits(n,b) then return true end if end for end if return false end function constant kinds = {" ", " odd ", " prime "} for i=1 to length(kinds) do printf(1,"First 20%sBrazilian numbers:\n", {kinds[i]}) integer c = 0, n = 7, p = 4 while true do if is_brazilian(n) then printf(1,"%d ",n) c += 1 if c==20 then printf(1,"\n\n") exit end if end if switch i case 1: n += 1 case 2: n += 2 case 3: p += 1; n = get_prime(p) end switch end while end for integer n = 7, c = 0 atom t0 = time(), t1 = time()+1 while c<100000 do if platform()!=JS and time()>t1 then printf(1,"checking %d [count:%d]...\r",{n,c}) t1 = time()+1 end if c += is_brazilian(n) n += 1 end while printf(1,"The %,dth Brazilian number: %d\n", {c,n-1}) ?elapsed(time()-t0)
http://rosettacode.org/wiki/Calendar
Calendar
Create a routine that will generate a text calendar for any year. Test the calendar by generating a calendar for the year 1969, on a device of the time. Choose one of the following devices: A line printer with a width of 132 characters. An IBM 3278 model 4 terminal (80×43 display with accented characters). Target formatting the months of the year to fit nicely across the 80 character width screen. Restrict number of lines in test output to 43. (Ideally, the program will generate well-formatted calendars for any page width from 20 characters up.) Kudos (κῦδος) for routines that also transition from Julian to Gregorian calendar. This task is inspired by Real Programmers Don't Use PASCAL by Ed Post, Datamation, volume 29 number 7, July 1983. THE REAL PROGRAMMER'S NATURAL HABITAT "Taped to the wall is a line-printer Snoopy calender for the year 1969." For further Kudos see task CALENDAR, where all code is to be in UPPERCASE. For economy of size, do not actually include Snoopy generation in either the code or the output, instead just output a place-holder. Related task   Five weekends
#Lingo
Lingo
---------------------------------------- -- @desc Class "Calendar" -- @file parent script "Calendar" ---------------------------------------- property _months property _weekdayStr property _refDateObj property _year property _calStr   on new (me) me._months = ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"] me._weekdayStr = "Mo Tu We Th Fr Sa Su" me._refDateObj = date(1905,1,2) return me end   on make (me, year) me._year = year me._calStr = "" -- prefill cal string with spaces emptyLine = bytearray(68,32).readRawString(68)&RETURN repeat with i = 1 to 38 put emptyLine after _calStr end repeat me._write (string(year), 32, 1) repeat with i = 1 to 12 me._writeMonth(i) end repeat return me._calStr end   on _writeMonth (me, monthNum) xOffset = (monthNum-1) mod 3 * 24 yOffset = (monthNum-1)/3 * 9 + 2 pre = (20 - me._months[monthNum].length)/2 me._write(me._months[monthNum], 1+xOffset+pre, 1+yOffset) me._write(me._weekdayStr, 1+xOffset, 2+yOffset) y = 3 x = ((date(me._year, monthNum, 1) - me._refDateObj) mod 7)+1 repeat with i = 1 to 31 if date(me._year, monthNum, i).month<>monthNum then exit repeat dayStr = string(i) if i<10 then put " " before dayStr me._write(dayStr, x*3-2+xOffset, y+yOffset) if x=7 then y = y+1 x = 1 else x = x+1 end if end repeat end   on _write (me, str, x, y) put str into char x to x+str.length-1 of line y of _calStr end
http://rosettacode.org/wiki/Brownian_tree
Brownian tree
Brownian tree You are encouraged to solve this task according to the task description, using any language you may know. Task Generate and draw a   Brownian Tree. A Brownian Tree is generated as a result of an initial seed, followed by the interaction of two processes. The initial "seed" is placed somewhere within the field. Where is not particularly important; it could be randomized, or it could be a fixed point. Particles are injected into the field, and are individually given a (typically random) motion pattern. When a particle collides with the seed or tree, its position is fixed, and it's considered to be part of the tree. Because of the lax rules governing the random nature of the particle's placement and motion, no two resulting trees are really expected to be the same, or even necessarily have the same general shape.
#Phix
Phix
-- demo\rosetta\BrownianTree.exw include pGUI.e Ihandle dlg, canvas cdCanvas cddbuffer, cdcanvas function redraw_cb(Ihandle /*ih*/, integer /*posx*/, integer /*posy*/) integer x,y,ox,oy integer {width, height} = IupGetIntInt(canvas, "DRAWSIZE") sequence grid = repeat(repeat(0,width),height) integer xy = floor(width*height*0.8) --atom t = time()+1 grid[floor(width/2)][floor(height/2)] = 1 cdCanvasActivate(cddbuffer) cdCanvasClear(cddbuffer) for i=1 to xy do x = rand(width) y = rand(height) ox = x oy = y while x>=1 and x<=width and y>=1 and y<=height do if grid[y][x] then grid[oy][ox] = 1 cdCanvasPixel(cddbuffer, ox, oy, #00FF00) exit end if ox = x x += rand(3)-2 oy = y y += rand(3)-2 end while -- -- if making the canvas bigger/resizeable, -- -- put this in so that you can kill it. -- if time()>=t then --  ?{i,xy} -- t = time()+1 -- end if end for cdCanvasFlush(cddbuffer) return IUP_DEFAULT end function function map_cb(Ihandle ih) cdcanvas = cdCreateCanvas(CD_IUP, ih) cddbuffer = cdCreateCanvas(CD_DBUFFER, cdcanvas) cdCanvasSetBackground(cddbuffer, CD_WHITE) cdCanvasSetForeground(cddbuffer, CD_RED) return IUP_DEFAULT end function IupOpen() canvas = IupCanvas(NULL) IupSetAttribute(canvas, "RASTERSIZE", "200x200") -- fixed size IupSetCallback(canvas, "MAP_CB", Icallback("map_cb")) dlg = IupDialog(canvas, "RESIZE=NO") IupSetAttribute(dlg, "TITLE", "Brownian Tree") IupSetCallback(canvas, "ACTION", Icallback("redraw_cb")) IupShow(dlg) if platform()!=JS then IupMainLoop() IupClose() end if
http://rosettacode.org/wiki/Bulls_and_cows
Bulls and cows
Bulls and Cows Task Create a four digit random number from the digits   1   to   9,   without duplication. The program should:   ask for guesses to this number   reject guesses that are malformed   print the score for the guess The score is computed as: The player wins if the guess is the same as the randomly chosen number, and the program ends. A score of one bull is accumulated for each digit in the guess that equals the corresponding digit in the randomly chosen initial number. A score of one cow is accumulated for each digit in the guess that also appears in the randomly chosen number, but in the wrong position. Related tasks   Bulls and cows/Player   Guess the number   Guess the number/With Feedback   Mastermind
#F.23
F#
  open System   let generate_number targetSize = let rnd = Random() let initial = Seq.initInfinite (fun _ -> rnd.Next(1,9)) initial |> Seq.distinct |> Seq.take(targetSize) |> Seq.toList   let countBulls guess target = let hits = List.map2 (fun g t -> if g = t then true else false) guess target List.filter (fun x -> x = true) hits |> List.length   let countCows guess target = let mutable score = 0 for g in guess do for t in target do if g = t then score <- score + 1 else score <- score score   let countScore guess target = let bulls = countBulls guess target let cows = countCows guess target (bulls, cows)   let playRound guess target = countScore guess target   let inline ctoi c : int = int c - int '0'   let lineToList (line: string) = let listc = Seq.map(fun c -> c |> string) line |> Seq.toList let conv = List.map(fun x -> Int32.Parse x) listc conv   let readLine() = let line = Console.ReadLine() if line <> null then if line.Length = 4 then Ok (lineToList line) else Error("Input guess must be 4 characters!") else Error("Input guess cannot be empty!")   let rec handleInput() = let line = readLine() match line with | Ok x -> x | Error s -> printfn "%A" s handleInput()   [<EntryPoint>] let main argv = let target = generate_number 4 let mutable shouldEnd = false while shouldEnd = false do let guess = handleInput() let (b, c) = playRound guess target printfn "Bulls: %i | Cows: %i" b c if b = 4 then shouldEnd <- true else shouldEnd <- false 0  
http://rosettacode.org/wiki/Caesar_cipher
Caesar cipher
Task Implement a Caesar cipher, both encoding and decoding. The key is an integer from 1 to 25. This cipher rotates (either towards left or right) the letters of the alphabet (A to Z). The encoding replaces each letter with the 1st to 25th next letter in the alphabet (wrapping Z to A). So key 2 encrypts "HI" to "JK", but key 20 encrypts "HI" to "BC". This simple "mono-alphabetic substitution cipher" provides almost no security, because an attacker who has the encoded message can either use frequency analysis to guess the key, or just try all 25 keys. Caesar cipher is identical to Vigenère cipher with a key of length 1. Also, Rot-13 is identical to Caesar cipher with key 13. Related tasks Rot-13 Substitution Cipher Vigenère Cipher/Cryptanalysis
#Ela
Ela
open number char monad io string   chars = "ABCDEFGHIJKLMOPQRSTUVWXYZ"   caesar _ _ [] = "" caesar op key (x::xs) = check shifted ++ caesar op key xs where orig = indexOf (string.upper $ toString x) chars shifted = orig `op` key check val | orig == -1 = x | val > 24 = trans $ val - 25 | val < 0 = trans $ 25 + val | else = trans shifted trans idx = chars:idx   cypher = caesar (+) decypher = caesar (-)   key = 2   do putStrLn "A string to encode:" str <- readStr putStr "Encoded string: " cstr <- return <| cypher key str put cstr putStrLn "" putStr "Decoded string: " put $ decypher key cstr
http://rosettacode.org/wiki/Calculating_the_value_of_e
Calculating the value of e
Task Calculate the value of   e. (e   is also known as   Euler's number   and   Napier's constant.) See details: Calculating the value of e
#Scheme
Scheme
  (import (rnrs))   (define (e) (sum (map (lambda (x) (/ 1.0 x)) (scanl (lambda (a x) (* a x)) 1 (enum-from-to 1 20)))))   (define (enum-from-to m n) (if (>= n m) (iterate-until (lambda (x) (>= x n)) (lambda (x) (+ 1 x)) m) '()))   (define (iterate-until p f x) (let loop ((vs (list x)) (h x)) (if (p h) (reverse vs) (loop (cons (f h) vs) (f h)))))   (define (sum xs) (fold-left + 0 xs))   (define-record-type scan (fields acc scan))   (define (scanl f start-value xs) (scan-scan (fold-left (lambda (a x) (let ((v (f (scan-acc a) x))) (make-scan v (cons v (scan-scan a))))) (make-scan start-value (cons start-value '())) xs)))   (display (e)) (newline)
http://rosettacode.org/wiki/Bulls_and_cows/Player
Bulls and cows/Player
Task Write a player of the Bulls and Cows game, rather than a scorer. The player should give intermediate answers that respect the scores to previous attempts. One method is to generate a list of all possible numbers that could be the answer, then to prune the list by keeping only those numbers that would give an equivalent score to how your last guess was scored. Your next guess can be any number from the pruned list. Either you guess correctly or run out of numbers to guess, which indicates a problem with the scoring. Related tasks   Bulls and cows   Guess the number   Guess the number/With Feedback (Player)
#Yabasic
Yabasic
  clear screen   guesses = 0   void = ran()   while(len(secret$) < 4) // zero not allowed n$ = chr$(int(ran(1) * 9) + 49) if not(instr(secret$, n$)) secret$ = secret$ + n$ wend   print " Secretly, my opponent just chose a number. But she didn't tell anyone!\n\t\t\t\t", secret$, "." print " I can however be given a score for my guesses."   for i = 1234 to 9876 if check(str$(i)) = 0 then available$ = available$ + " " + str$(i) k = k +1 end if next i   available$ = trim$(available$) // remove the surplus, leading space   while(true) print print "Currently holding ", k, " possible numbers. "   guess$ =word$(available$, 1 + int(k * ran(1)), " ") print "Computer guessed ", guess$, " & got ";   bulls = 0 cows = 0 guesses = guesses + 1   r$ = score$(guess$, secret$)   bulls = val(word$(r$, 1, ",")) cows = val(word$(r$, 2, ","))   print bulls, " bull(s), and ", cows, " cow(s)."   if guess$ = secret$ then print "\nComputer won after ", guesses, " guesses!"; print " That took ", right$(time$, 1), " seconds. ENDED!" break end if kk = 0 new$ = ""   for j = 1 to k bullsT = 0 cowsT = 0   possible$ = word$(available$, j, " ")   r$ = score$(guess$, possible$)   bullsT = val(word$(r$, 1, ",")) cowsT = val(word$(r$, 2, ","))   if (bullsT = bulls) and ( cowsT = cows) then new$ = new$ + " " + possible$ // keep those with same score kk = kk + 1 end if next j   available$ = trim$(new$) k = kk   wend   sub score$(a$, b$) // return as a csv string the number of bulls & cows. local i, c$, bulls, cows   bulls = 0 : cows = 0 for i = 1 to 4 c$ = mid$(a$, i, 1) if mid$(b$, i, 1) = c$ then bulls = bulls + 1 else if (instr(b$, c$) <> 0) and (instr(b$, c$) <> i) cows = cows + 1 end if next i return str$(bulls) + "," + str$(cows) end sub   sub check(i$) local t, i, j   t = 0 // zero flags available: 1 means not available for i = 1 to 3 for j = i + 1 to 4 if mid$(i$, i, 1) = mid$(i$, j, 1) t = 1 next j next i if instr(i$, "0") t = 1 return t end sub   sub word$(l$, i, d$) local c$(1), n   n = token(l$, c$(), d$) return c$(i) end sub
http://rosettacode.org/wiki/Call_a_function
Call a function
Task Demonstrate the different syntax and semantics provided for calling a function. This may include:   Calling a function that requires no arguments   Calling a function with a fixed number of arguments   Calling a function with optional arguments   Calling a function with a variable number of arguments   Calling a function with named arguments   Using a function in statement context   Using a function in first-class context within an expression   Obtaining the return value of a function   Distinguishing built-in functions and user-defined functions   Distinguishing subroutines and functions   Stating whether arguments are passed by value or by reference   Is partial application possible and how This task is not about defining functions.
#jq
jq
  # Calling a function that requires no arguments: f() = print("Hello world!") f()     # Calling a function with a fixed number of arguments: function f(x, y, z) x*y - z^2 end   f(3, 4, 2)     # Calling a function with optional arguments: # Note Julia uses multiple dispatch based on argument number and type, so # f() is always different from f(x) unless default arguments are used, as in:   pimultiple(mult=1.0) = pi * mult # so pimultiple() defaults to pi * (1.0) or pi     # Calling a function with a variable number of arguments:   f(a,b,x...) = reduce(+, 0, x) - a - b     # here a and b are single arguments, but x is a tuple of x plus whatever follows x, so: a = b = c = d = e = 3 f(a,b,c) # x within the function is (c) so == 0 + c - a - b f(a,b,c,d,e) # x is a tuple == (c,d,e) so == (0 + c + d + e) - a - b f(a,b) # x is () so == 0 - a - b     # Calling a function with named arguments: # Functions with keyword arguments are defined using a semicolon in the function signature, # as in # function plot(x, y; style="solid", width=1, color="black") # # When the function is called, the semicolon is optional, so plot here can be # either called with plot(x, y, width=2) or less commonly as plot(x, y; width=2).     # Using a function in statement context: # Any function can be used as a variable by its name.   circlearea(x) = x^2 * pi map(circlearea, [r1, r2, r3, r4])     # Using a function in first-class context within an expression: cylindervolume = circlearea(r) * h     # Obtaining the return value of a function: radius = 2.5 area = circlearea(2.5)     # Distinguishing built-in functions and user-defined functions: # Julia does not attempt to distinguish these in any special way, # but at the REPL command line there is ? help available for builtin # functions that would not generally be available for the user-defined ones.     # Distinguishing subroutines and functions: # All subroutines are called functions in Julia, regardless of whether they return values.     # Stating whether arguments are passed by value or by reference: # As in Python, all arguments are passed by pointer reference, but assignment to a passed argument # only changes the variable within the function. Assignment to the values referenced by the argument ## DOES however change those values. For instance:   a = 3 b = [3] c = [3]   function f(x, y) a = 0 b[1] = 0 c = [0] end # a and c are now unchanged but b = [0]     # Is partial application possible and how: # In Julia, there are many different ways to compose functions. In particular, # Julia has an "arrow" operator -> that may be used to curry other functions.   f(a, b) = a^2 + a + b v = [4, 6, 8] map(x -> f(x, 10), v) # v = [30, 52, 82]  
http://rosettacode.org/wiki/Catalan_numbers
Catalan numbers
Catalan numbers You are encouraged to solve this task according to the task description, using any language you may know. Catalan numbers are a sequence of numbers which can be defined directly: C n = 1 n + 1 ( 2 n n ) = ( 2 n ) ! ( n + 1 ) ! n !  for  n ≥ 0. {\displaystyle C_{n}={\frac {1}{n+1}}{2n \choose n}={\frac {(2n)!}{(n+1)!\,n!}}\qquad {\mbox{ for }}n\geq 0.} Or recursively: C 0 = 1 and C n + 1 = ∑ i = 0 n C i C n − i for  n ≥ 0 ; {\displaystyle C_{0}=1\quad {\mbox{and}}\quad C_{n+1}=\sum _{i=0}^{n}C_{i}\,C_{n-i}\quad {\text{for }}n\geq 0;} Or alternatively (also recursive): C 0 = 1 and C n = 2 ( 2 n − 1 ) n + 1 C n − 1 , {\displaystyle C_{0}=1\quad {\mbox{and}}\quad C_{n}={\frac {2(2n-1)}{n+1}}C_{n-1},} Task Implement at least one of these algorithms and print out the first 15 Catalan numbers with each. Memoization   is not required, but may be worth the effort when using the second method above. Related tasks Catalan numbers/Pascal's triangle Evaluate binomial coefficients
#ooRexx
ooRexx
loop i = 0 to 15 say "catI("i") =" .catalan~catI(i) say "catR1("i") =" .catalan~catR1(i) say "catR2("i") =" .catalan~catR2(i) end   -- This is implemented as static members on a class object -- so that the code is able to keep state information between calls. This -- memoization will speed up things like factorial calls by remembering previous -- results. ::class catalan -- initialize the class object ::method init class expose facts catI catR1 catR2 facts = .table~new catI = .table~new catR1 = .table~new catR2 = .table~new -- seed a few items facts[0] = 1 facts[1] = 1 facts[2] = 2 catI[0] = 1 catR1[0] = 1 catR2[0] = 1   -- private factorial method ::method fact private class expose facts use arg n -- see if we've calculated this before if facts~hasIndex(n) then return facts[n] numeric digits 120   fact = 1 loop i = 2 to n fact *= i end -- save this result facts[n] = fact return fact   ::method catI class expose catI use arg n numeric digits 20   res = catI[n] if res == .nil then do -- dividing by 1 removes insignificant trailing 0s res = (self~fact(2 * n)/(self~fact(n + 1) * self~fact(n))) / 1 catI[n] = res end return res   ::method catR1 class expose catR1 use arg n numeric digits 20   if catR1~hasIndex(n) then return catR1[n] sum = 0 loop i = 0 to n - 1 sum += self~catR1(i) * self~catR1(n - 1 - i) end -- remove insignificant trailing 0s sum = sum / 1 catR1[n] = sum return sum   ::method catR2 class expose catR2 use arg n numeric digits 20   res = catR2[n] if res == .nil then do res = ((2 * (2 * n - 1) * self~catR2(n - 1)) / (n + 1)) catR2[n] = res end return res
http://rosettacode.org/wiki/Brace_expansion
Brace expansion
Brace expansion is a type of parameter expansion made popular by Unix shells, where it allows users to specify multiple similar string parameters without having to type them all out. E.g. the parameter enable_{audio,video} would be interpreted as if both enable_audio and enable_video had been specified. Task[edit] Write a function that can perform brace expansion on any input string, according to the following specification. Demonstrate how it would be used, and that it passes the four test cases given below. Specification In the input string, balanced pairs of braces containing comma-separated substrings (details below) represent alternations that specify multiple alternatives which are to appear at that position in the output. In general, one can imagine the information conveyed by the input string as a tree of nested alternations interspersed with literal substrings, as shown in the middle part of the following diagram: It{{em,alic}iz,erat}e{d,} parse  ―――――▶ ‌ It ⎧ ⎨ ⎩ ⎧ ⎨ ⎩ em ⎫ ⎬ ⎭ alic iz ⎫ ⎬ ⎭ erat e ⎧ ⎨ ⎩ d ⎫ ⎬ ⎭ ‌ expand  ―――――▶ ‌ Itemized Itemize Italicized Italicize Iterated Iterate input string alternation tree output (list of strings) This tree can in turn be transformed into the intended list of output strings by, colloquially speaking, determining all the possible ways to walk through it from left to right while only descending into one branch of each alternation one comes across (see the right part of the diagram). When implementing it, one can of course combine the parsing and expansion into a single algorithm, but this specification discusses them separately for the sake of clarity. Expansion of alternations can be more rigorously described by these rules: a ⎧ ⎨ ⎩ 2 ⎫ ⎬ ⎭ 1 b ⎧ ⎨ ⎩ X ⎫ ⎬ ⎭ Y X c ⟶ a2bXc a2bYc a2bXc a1bXc a1bYc a1bXc An alternation causes the list of alternatives that will be produced by its parent branch to be increased 𝑛-fold, each copy featuring one of the 𝑛 alternatives produced by the alternation's child branches, in turn, at that position. This means that multiple alternations inside the same branch are cumulative  (i.e. the complete list of alternatives produced by a branch is the string-concatenating "Cartesian product" of its parts). All alternatives (even duplicate and empty ones) are preserved, and they are ordered like the examples demonstrate  (i.e. "lexicographically" with regard to the alternations). The alternatives produced by the root branch constitute the final output. Parsing the input string involves some additional complexity to deal with escaped characters and "incomplete" brace pairs: a\\{\\\{b,c\,d} ⟶ a\\ ⎧ ⎨ ⎩ \\\{b ⎫ ⎬ ⎭ c\,d {a,b{c{,{d}}e}f ⟶ {a,b{c ⎧ ⎨ ⎩ ‌ ⎫ ⎬ ⎭ {d} e}f An unescaped backslash which precedes another character, escapes that character (to force it to be treated as literal). The backslashes are passed along to the output unchanged. Balanced brace pairs are identified by, conceptually, going through the string from left to right and associating each unescaped closing brace that is encountered with the nearest still unassociated unescaped opening brace to its left (if any). Furthermore, each unescaped comma is associated with the innermost brace pair that contains it (if any). With that in mind: Each brace pair that has at least one comma associated with it, forms an alternation (whose branches are the brace pair's contents split at its commas). The associated brace and comma characters themselves do not become part of the output. Brace characters from pairs without any associated comma, as well as unassociated brace and comma characters, as well as all characters that are not covered by the preceding rules, are instead treated as literals. For every possible input string, your implementation should produce exactly the output which this specification mandates. Please comply with this even when it's inconvenient, to ensure that all implementations are comparable. However, none of the above should be interpreted as instructions (or even recommendations) for how to implement it. Try to come up with a solution that is idiomatic in your programming language. (See #Perl for a reference implementation.) Test Cases Input (single string) Ouput (list/array of strings) ~/{Downloads,Pictures}/*.{jpg,gif,png} ~/Downloads/*.jpg ~/Downloads/*.gif ~/Downloads/*.png ~/Pictures/*.jpg ~/Pictures/*.gif ~/Pictures/*.png It{{em,alic}iz,erat}e{d,}, please. Itemized, please. Itemize, please. Italicized, please. Italicize, please. Iterated, please. Iterate, please. {,{,gotta have{ ,\, again\, }}more }cowbell! cowbell! more cowbell! gotta have more cowbell! gotta have\, again\, more cowbell! {}} some }{,{\\{ edge, edge} \,}{ cases, {here} \\\\\} {}} some }{,{\\ edge \,}{ cases, {here} \\\\\} {}} some }{,{\\ edge \,}{ cases, {here} \\\\\} Other tasks related to string operations: Metrics Array length String length Copy a string Empty string  (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff  (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet   Brace_expansion_using_ranges
#Tcl
Tcl
package require Tcl 8.6   proc combine {cases1 cases2 {insert ""}} { set result {} foreach c1 $cases1 { foreach c2 $cases2 { lappend result $c1$insert$c2 } } return $result } proc expand {string *expvar} { upvar 1 ${*expvar} expanded set a {} set result {} set depth 0 foreach token [regexp -all -inline {(?:[^\\{},]|\\.)+|[\\{},]} $string] { switch $token { "," { if {$depth == 0} { lappend result {*}[commatize $a] set a {} set expanded 1 continue } } "\{" {incr depth 1} "\}" {incr depth -1} } append a $token } lappend result {*}[commatize $a] return $result } proc commatize {string} { set current {{}} set depth 0 foreach token [regexp -all -inline {(?:[^\\{},]|\\.)+|[\\{},]} $string] { switch $token { "\{" { if {[incr depth] == 1} { set collect {} continue } } "\}" { if {[incr depth -1] == 0} { set foundComma 0 set exp [expand $collect foundComma] if {!$foundComma} { set exp [lmap c [commatize $collect] {set c \{$c\}}] } set current [combine $current $exp] continue } elseif {$depth < 0} { set depth 0 } } } if {$depth} { append collect $token } else { set current [lmap s $current {set s $s$token}] } } if {$depth} { set current [combine $current [commatize $collect] "\{"] } return $current }
http://rosettacode.org/wiki/Brazilian_numbers
Brazilian numbers
Brazilian numbers are so called as they were first formally presented at the 1994 math Olympiad Olimpiada Iberoamericana de Matematica in Fortaleza, Brazil. Brazilian numbers are defined as: The set of positive integer numbers where each number N has at least one natural number B where 1 < B < N-1 where the representation of N in base B has all equal digits. E.G. 1, 2 & 3 can not be Brazilian; there is no base B that satisfies the condition 1 < B < N-1. 4 is not Brazilian; 4 in base 2 is 100. The digits are not all the same. 5 is not Brazilian; 5 in base 2 is 101, in base 3 is 12. There is no representation where the digits are the same. 6 is not Brazilian; 6 in base 2 is 110, in base 3 is 20, in base 4 is 12. There is no representation where the digits are the same. 7 is Brazilian; 7 in base 2 is 111. There is at least one representation where the digits are all the same. 8 is Brazilian; 8 in base 3 is 22. There is at least one representation where the digits are all the same. and so on... All even integers 2P >= 8 are Brazilian because 2P = 2(P-1) + 2, which is 22 in base P-1 when P-1 > 2. That becomes true when P >= 4. More common: for all all integers R and S, where R > 1 and also S-1 > R, then R*S is Brazilian because R*S = R(S-1) + R, which is RR in base S-1 The only problematic numbers are squares of primes, where R = S. Only 11^2 is brazilian to base 3. All prime integers, that are brazilian, can only have the digit 1. Otherwise one could factor out the digit, therefore it cannot be a prime number. Mostly in form of 111 to base Integer(sqrt(prime number)). Must be an odd count of 1 to stay odd like primes > 2 Task Write a routine (function, whatever) to determine if a number is Brazilian and use the routine to show here, on this page; the first 20 Brazilian numbers; the first 20 odd Brazilian numbers; the first 20 prime Brazilian numbers; See also OEIS:A125134 - Brazilian numbers OEIS:A257521 - Odd Brazilian numbers OEIS:A085104 - Prime Brazilian numbers
#Python
Python
'''Brazilian numbers'''   from itertools import count, islice     # isBrazil :: Int -> Bool def isBrazil(n): '''True if n is a Brazilian number, in the sense of OEIS:A125134. ''' return 7 <= n and ( 0 == n % 2 or any( map(monoDigit(n), range(2, n - 1)) ) )     # monoDigit :: Int -> Int -> Bool def monoDigit(n): '''True if all the digits of n, in the given base, are the same. ''' def go(base): def g(b, n): (q, d) = divmod(n, b)   def p(qr): return d != qr[1] or 0 == qr[0]   def f(qr): return divmod(qr[0], b) return d == until(p)(f)( (q, d) )[1] return g(base, n) return go     # -------------------------- TEST -------------------------- # main :: IO () def main(): '''First 20 members each of: OEIS:A125134 OEIS:A257521 OEIS:A085104 ''' for kxs in ([ (' ', count(1)), (' odd ', count(1, 2)), (' prime ', primes()) ]): print( 'First 20' + kxs[0] + 'Brazilians:\n' + showList(take(20)(filter(isBrazil, kxs[1]))) + '\n' )     # ------------------- GENERIC FUNCTIONS --------------------   # primes :: [Int] def primes(): ''' Non finite sequence of prime numbers. ''' n = 2 dct = {} while True: if n in dct: for p in dct[n]: dct.setdefault(n + p, []).append(p) del dct[n] else: yield n dct[n * n] = [n] n = 1 + n     # showList :: [a] -> String def showList(xs): '''Stringification of a list.''' return '[' + ','.join(str(x) for x in xs) + ']'     # take :: Int -> [a] -> [a] # take :: Int -> String -> String def take(n): '''The prefix of xs of length n, or xs itself if n > length xs. ''' def go(xs): return ( xs[0:n] if isinstance(xs, (list, tuple)) else list(islice(xs, n)) ) return go     # until :: (a -> Bool) -> (a -> a) -> a -> a def until(p): '''The result of repeatedly applying f until p holds. The initial seed value is x. ''' def go(f): def g(x): v = x while not p(v): v = f(v) return v return g return go     # MAIN --- if __name__ == '__main__': main()
http://rosettacode.org/wiki/Calendar
Calendar
Create a routine that will generate a text calendar for any year. Test the calendar by generating a calendar for the year 1969, on a device of the time. Choose one of the following devices: A line printer with a width of 132 characters. An IBM 3278 model 4 terminal (80×43 display with accented characters). Target formatting the months of the year to fit nicely across the 80 character width screen. Restrict number of lines in test output to 43. (Ideally, the program will generate well-formatted calendars for any page width from 20 characters up.) Kudos (κῦδος) for routines that also transition from Julian to Gregorian calendar. This task is inspired by Real Programmers Don't Use PASCAL by Ed Post, Datamation, volume 29 number 7, July 1983. THE REAL PROGRAMMER'S NATURAL HABITAT "Taped to the wall is a line-printer Snoopy calender for the year 1969." For further Kudos see task CALENDAR, where all code is to be in UPPERCASE. For economy of size, do not actually include Snoopy generation in either the code or the output, instead just output a place-holder. Related task   Five weekends
#Lua
Lua
function print_cal(year) local months={"JANUARY","FEBRUARY","MARCH","APRIL","MAY","JUNE", "JULY","AUGUST","SEPTEMBER","OCTOBER","NOVEMBER","DECEMBER"} local daysTitle="MO TU WE TH FR SA SU" local daysPerMonth={31,28,31,30,31,30,31,31,30,31,30,31} local startday=((year-1)*365+math.floor((year-1)/4)-math.floor((year-1)/100)+math.floor((year-1)/400))%7 if year%4==0 and year%100~=0 or year%400==0 then daysPerMonth[2]=29 end local sep=5 local monthwidth=daysTitle:len() local calwidth=3*monthwidth+2*sep   function center(str, width) local fill1=math.floor((width-str:len())/2) local fill2=width-str:len()-fill1 return string.rep(" ",fill1)..str..string.rep(" ",fill2) end   function makeMonth(name, skip,days) local cal={ center(name,monthwidth), daysTitle } local curday=1-skip while #cal<9 do line={} for i=1,7 do if curday<1 or curday>days then line[i]=" " else line[i]=string.format("%2d",curday) end curday=curday+1 end cal[#cal+1]=table.concat(line," ") end return cal end   local calendar={} for i,month in ipairs(months) do local dpm=daysPerMonth[i] calendar[i]=makeMonth(month, startday, dpm) startday=(startday+dpm)%7 end     print(center("[SNOOPY]",calwidth),"\n") print(center("--- "..year.." ---",calwidth),"\n")   for q=0,3 do for l=1,9 do line={} for m=1,3 do line[m]=calendar[q*3+m][l] end print(table.concat(line,string.rep(" ",sep))) end end end   print_cal(1969)
http://rosettacode.org/wiki/Brownian_tree
Brownian tree
Brownian tree You are encouraged to solve this task according to the task description, using any language you may know. Task Generate and draw a   Brownian Tree. A Brownian Tree is generated as a result of an initial seed, followed by the interaction of two processes. The initial "seed" is placed somewhere within the field. Where is not particularly important; it could be randomized, or it could be a fixed point. Particles are injected into the field, and are individually given a (typically random) motion pattern. When a particle collides with the seed or tree, its position is fixed, and it's considered to be part of the tree. Because of the lax rules governing the random nature of the particle's placement and motion, no two resulting trees are really expected to be the same, or even necessarily have the same general shape.
#PicoLisp
PicoLisp
(load "@lib/simul.l")   (de brownianTree (File Size Cnt) (let Img (grid Size Size) (put Img (/ Size 2) (/ Size 2) 'pix T) (use (P Q) (do Cnt (setq P (get Img (rand 1 Size) (rand 1 Size))) (loop (setq Q ((if2 (rand T) (rand T) north east south west) P)) (T (; Q pix) (put P 'pix T)) (setq P (or Q (get Img (rand 1 Size) (rand 1 Size)))) ) ) ) (out "img.pbm" (prinl "P1") (prinl Size " " Size) (for L Img (for This L (prin (if (: pix) 1 0)) ) (prinl) ) ) ) )
http://rosettacode.org/wiki/Bulls_and_cows
Bulls and cows
Bulls and Cows Task Create a four digit random number from the digits   1   to   9,   without duplication. The program should:   ask for guesses to this number   reject guesses that are malformed   print the score for the guess The score is computed as: The player wins if the guess is the same as the randomly chosen number, and the program ends. A score of one bull is accumulated for each digit in the guess that equals the corresponding digit in the randomly chosen initial number. A score of one cow is accumulated for each digit in the guess that also appears in the randomly chosen number, but in the wrong position. Related tasks   Bulls and cows/Player   Guess the number   Guess the number/With Feedback   Mastermind
#FreeBASIC
FreeBASIC
function get_digit( num as uinteger, ps as uinteger ) as uinteger return (num mod 10^(ps+1))\10^ps end function   function is_malformed( num as uinteger ) as boolean if num > 9876 then return true dim as uinteger i, j for i = 0 to 2 for j = i+1 to 3 if get_digit( num, j ) = get_digit( num, i ) then return true next j next i return false end function   function make_number() as uinteger dim as uinteger num = 0 while is_malformed(num) num = int(rnd*9877) wend return num end function   randomize timer   dim as uinteger count=0, num=make_number(), guess=0 dim as uinteger cows, bulls, i, j   while guess <> num count += 1 do print "Guess a number. " input guess loop while is_malformed(guess)   cows = 0 bulls = 0   for i = 0 to 3 for j = 0 to 3 if get_digit( num, i ) = get_digit( guess, j ) then if i= j then bulls += 1 if i<>j then cows += 1 end if next j next i print using "You scored # bulls and # cows."; bulls; cows wend   print using "Correct. That took you ### guesses."; count
http://rosettacode.org/wiki/Caesar_cipher
Caesar cipher
Task Implement a Caesar cipher, both encoding and decoding. The key is an integer from 1 to 25. This cipher rotates (either towards left or right) the letters of the alphabet (A to Z). The encoding replaces each letter with the 1st to 25th next letter in the alphabet (wrapping Z to A). So key 2 encrypts "HI" to "JK", but key 20 encrypts "HI" to "BC". This simple "mono-alphabetic substitution cipher" provides almost no security, because an attacker who has the encoded message can either use frequency analysis to guess the key, or just try all 25 keys. Caesar cipher is identical to Vigenère cipher with a key of length 1. Also, Rot-13 is identical to Caesar cipher with key 13. Related tasks Rot-13 Substitution Cipher Vigenère Cipher/Cryptanalysis
#Elena
Elena
import system'routines; import system'math; import extensions; import extensions'text;   const string Letters = "abcdefghijklmnopqrstuvwxyz"; const string BigLetters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; const string TestText = "Pack my box with five dozen liquor jugs."; const int Key = 12;   class Encrypting : Enumerator { int theKey; Enumerator theEnumerator;   constructor(int key, string text) { theKey := key; theEnumerator := text.enumerator(); }   bool next() => theEnumerator;   reset() => theEnumerator;   enumerable() => theEnumerator;   get() { var ch := theEnumerator.get();   var index := Letters.indexOf(0, ch);   if (-1 < index) { ^ Letters[(theKey+index).mod:26] } else { index := BigLetters.indexOf(0, ch); if (-1 < index) { ^ BigLetters[(theKey+index).mod:26] } else { ^ ch } } } }   extension encryptOp { encrypt(key) = new Encrypting(key, self).summarize(new StringWriter());   decrypt(key) = new Encrypting(26 - key, self).summarize(new StringWriter()); }   public program() { console.printLine("Original text :",TestText);   var encryptedText := TestText.encrypt:Key;   console.printLine("Encrypted text:",encryptedText);   var decryptedText := encryptedText.decrypt:Key;   console.printLine("Decrypted text:",decryptedText);   console.readChar() }
http://rosettacode.org/wiki/Calculating_the_value_of_e
Calculating the value of e
Task Calculate the value of   e. (e   is also known as   Euler's number   and   Napier's constant.) See details: Calculating the value of e
#Seed7
Seed7
$ include "seed7_05.s7i"; include "float.s7i";   const float: EPSILON is 1.0e-15;   const proc: main is func local var integer: fact is 1; var float: e is 2.0; var float: e0 is 0.0; var integer: n is 2; begin repeat e0 := e; fact *:= n; incr(n); e +:= 1.0 / flt(fact); until abs(e - e0) < EPSILON; writeln("e = " <& e digits 15); end func;
http://rosettacode.org/wiki/Calculating_the_value_of_e
Calculating the value of e
Task Calculate the value of   e. (e   is also known as   Euler's number   and   Napier's constant.) See details: Calculating the value of e
#Sidef
Sidef
func calculate_e(n=50) { sum(0..n, {|k| 1/k! }) }   say calculate_e() say calculate_e(69).as_dec(100)
http://rosettacode.org/wiki/Bulls_and_cows/Player
Bulls and cows/Player
Task Write a player of the Bulls and Cows game, rather than a scorer. The player should give intermediate answers that respect the scores to previous attempts. One method is to generate a list of all possible numbers that could be the answer, then to prune the list by keeping only those numbers that would give an equivalent score to how your last guess was scored. Your next guess can be any number from the pruned list. Either you guess correctly or run out of numbers to guess, which indicates a problem with the scoring. Related tasks   Bulls and cows   Guess the number   Guess the number/With Feedback (Player)
#zkl
zkl
d9:="123456789"; choices:=Walker.cproduct(d9,d9,d9,d9).pump(List,// lazy,-->3024, order is important fcn(list){ s:=list.concat(); (s.unique().len()==4) and s or Void.Skip }); do{ guess:=choices[(0).random(choices.len())]; score:=ask("My guess is %s. How many bulls and cows? ".fmt(guess)).strip(); bulls,cows:=score.split("").apply("toInt"); // "12"-->(1,2) choices=choices.filter('wrap(c){ bulls==c.zipWith('==,guess).sum(0) and // 0 + True == 1 cows ==c.zipWith('wrap(a,b){ a!=b and guess.holds(a) },guess).sum(0) }); }while(choices.len()>1);   if(not choices) "Nothing fits the scores you gave.".println(); else "Solution found: ".println(choices[0]);
http://rosettacode.org/wiki/Call_a_function
Call a function
Task Demonstrate the different syntax and semantics provided for calling a function. This may include:   Calling a function that requires no arguments   Calling a function with a fixed number of arguments   Calling a function with optional arguments   Calling a function with a variable number of arguments   Calling a function with named arguments   Using a function in statement context   Using a function in first-class context within an expression   Obtaining the return value of a function   Distinguishing built-in functions and user-defined functions   Distinguishing subroutines and functions   Stating whether arguments are passed by value or by reference   Is partial application possible and how This task is not about defining functions.
#Julia
Julia
  # Calling a function that requires no arguments: f() = print("Hello world!") f()     # Calling a function with a fixed number of arguments: function f(x, y, z) x*y - z^2 end   f(3, 4, 2)     # Calling a function with optional arguments: # Note Julia uses multiple dispatch based on argument number and type, so # f() is always different from f(x) unless default arguments are used, as in:   pimultiple(mult=1.0) = pi * mult # so pimultiple() defaults to pi * (1.0) or pi     # Calling a function with a variable number of arguments:   f(a,b,x...) = reduce(+, 0, x) - a - b     # here a and b are single arguments, but x is a tuple of x plus whatever follows x, so: a = b = c = d = e = 3 f(a,b,c) # x within the function is (c) so == 0 + c - a - b f(a,b,c,d,e) # x is a tuple == (c,d,e) so == (0 + c + d + e) - a - b f(a,b) # x is () so == 0 - a - b     # Calling a function with named arguments: # Functions with keyword arguments are defined using a semicolon in the function signature, # as in # function plot(x, y; style="solid", width=1, color="black") # # When the function is called, the semicolon is optional, so plot here can be # either called with plot(x, y, width=2) or less commonly as plot(x, y; width=2).     # Using a function in statement context: # Any function can be used as a variable by its name.   circlearea(x) = x^2 * pi map(circlearea, [r1, r2, r3, r4])     # Using a function in first-class context within an expression: cylindervolume = circlearea(r) * h     # Obtaining the return value of a function: radius = 2.5 area = circlearea(2.5)     # Distinguishing built-in functions and user-defined functions: # Julia does not attempt to distinguish these in any special way, # but at the REPL command line there is ? help available for builtin # functions that would not generally be available for the user-defined ones.     # Distinguishing subroutines and functions: # All subroutines are called functions in Julia, regardless of whether they return values.     # Stating whether arguments are passed by value or by reference: # As in Python, all arguments are passed by pointer reference, but assignment to a passed argument # only changes the variable within the function. Assignment to the values referenced by the argument ## DOES however change those values. For instance:   a = 3 b = [3] c = [3]   function f(x, y) a = 0 b[1] = 0 c = [0] end # a and c are now unchanged but b = [0]     # Is partial application possible and how: # In Julia, there are many different ways to compose functions. In particular, # Julia has an "arrow" operator -> that may be used to curry other functions.   f(a, b) = a^2 + a + b v = [4, 6, 8] map(x -> f(x, 10), v) # v = [30, 52, 82]  
http://rosettacode.org/wiki/Catalan_numbers
Catalan numbers
Catalan numbers You are encouraged to solve this task according to the task description, using any language you may know. Catalan numbers are a sequence of numbers which can be defined directly: C n = 1 n + 1 ( 2 n n ) = ( 2 n ) ! ( n + 1 ) ! n !  for  n ≥ 0. {\displaystyle C_{n}={\frac {1}{n+1}}{2n \choose n}={\frac {(2n)!}{(n+1)!\,n!}}\qquad {\mbox{ for }}n\geq 0.} Or recursively: C 0 = 1 and C n + 1 = ∑ i = 0 n C i C n − i for  n ≥ 0 ; {\displaystyle C_{0}=1\quad {\mbox{and}}\quad C_{n+1}=\sum _{i=0}^{n}C_{i}\,C_{n-i}\quad {\text{for }}n\geq 0;} Or alternatively (also recursive): C 0 = 1 and C n = 2 ( 2 n − 1 ) n + 1 C n − 1 , {\displaystyle C_{0}=1\quad {\mbox{and}}\quad C_{n}={\frac {2(2n-1)}{n+1}}C_{n-1},} Task Implement at least one of these algorithms and print out the first 15 Catalan numbers with each. Memoization   is not required, but may be worth the effort when using the second method above. Related tasks Catalan numbers/Pascal's triangle Evaluate binomial coefficients
#PARI.2FGP
PARI/GP
catalan(n)=binomial(2*n,n+1)/n
http://rosettacode.org/wiki/Brace_expansion
Brace expansion
Brace expansion is a type of parameter expansion made popular by Unix shells, where it allows users to specify multiple similar string parameters without having to type them all out. E.g. the parameter enable_{audio,video} would be interpreted as if both enable_audio and enable_video had been specified. Task[edit] Write a function that can perform brace expansion on any input string, according to the following specification. Demonstrate how it would be used, and that it passes the four test cases given below. Specification In the input string, balanced pairs of braces containing comma-separated substrings (details below) represent alternations that specify multiple alternatives which are to appear at that position in the output. In general, one can imagine the information conveyed by the input string as a tree of nested alternations interspersed with literal substrings, as shown in the middle part of the following diagram: It{{em,alic}iz,erat}e{d,} parse  ―――――▶ ‌ It ⎧ ⎨ ⎩ ⎧ ⎨ ⎩ em ⎫ ⎬ ⎭ alic iz ⎫ ⎬ ⎭ erat e ⎧ ⎨ ⎩ d ⎫ ⎬ ⎭ ‌ expand  ―――――▶ ‌ Itemized Itemize Italicized Italicize Iterated Iterate input string alternation tree output (list of strings) This tree can in turn be transformed into the intended list of output strings by, colloquially speaking, determining all the possible ways to walk through it from left to right while only descending into one branch of each alternation one comes across (see the right part of the diagram). When implementing it, one can of course combine the parsing and expansion into a single algorithm, but this specification discusses them separately for the sake of clarity. Expansion of alternations can be more rigorously described by these rules: a ⎧ ⎨ ⎩ 2 ⎫ ⎬ ⎭ 1 b ⎧ ⎨ ⎩ X ⎫ ⎬ ⎭ Y X c ⟶ a2bXc a2bYc a2bXc a1bXc a1bYc a1bXc An alternation causes the list of alternatives that will be produced by its parent branch to be increased 𝑛-fold, each copy featuring one of the 𝑛 alternatives produced by the alternation's child branches, in turn, at that position. This means that multiple alternations inside the same branch are cumulative  (i.e. the complete list of alternatives produced by a branch is the string-concatenating "Cartesian product" of its parts). All alternatives (even duplicate and empty ones) are preserved, and they are ordered like the examples demonstrate  (i.e. "lexicographically" with regard to the alternations). The alternatives produced by the root branch constitute the final output. Parsing the input string involves some additional complexity to deal with escaped characters and "incomplete" brace pairs: a\\{\\\{b,c\,d} ⟶ a\\ ⎧ ⎨ ⎩ \\\{b ⎫ ⎬ ⎭ c\,d {a,b{c{,{d}}e}f ⟶ {a,b{c ⎧ ⎨ ⎩ ‌ ⎫ ⎬ ⎭ {d} e}f An unescaped backslash which precedes another character, escapes that character (to force it to be treated as literal). The backslashes are passed along to the output unchanged. Balanced brace pairs are identified by, conceptually, going through the string from left to right and associating each unescaped closing brace that is encountered with the nearest still unassociated unescaped opening brace to its left (if any). Furthermore, each unescaped comma is associated with the innermost brace pair that contains it (if any). With that in mind: Each brace pair that has at least one comma associated with it, forms an alternation (whose branches are the brace pair's contents split at its commas). The associated brace and comma characters themselves do not become part of the output. Brace characters from pairs without any associated comma, as well as unassociated brace and comma characters, as well as all characters that are not covered by the preceding rules, are instead treated as literals. For every possible input string, your implementation should produce exactly the output which this specification mandates. Please comply with this even when it's inconvenient, to ensure that all implementations are comparable. However, none of the above should be interpreted as instructions (or even recommendations) for how to implement it. Try to come up with a solution that is idiomatic in your programming language. (See #Perl for a reference implementation.) Test Cases Input (single string) Ouput (list/array of strings) ~/{Downloads,Pictures}/*.{jpg,gif,png} ~/Downloads/*.jpg ~/Downloads/*.gif ~/Downloads/*.png ~/Pictures/*.jpg ~/Pictures/*.gif ~/Pictures/*.png It{{em,alic}iz,erat}e{d,}, please. Itemized, please. Itemize, please. Italicized, please. Italicize, please. Iterated, please. Iterate, please. {,{,gotta have{ ,\, again\, }}more }cowbell! cowbell! more cowbell! gotta have more cowbell! gotta have\, again\, more cowbell! {}} some }{,{\\{ edge, edge} \,}{ cases, {here} \\\\\} {}} some }{,{\\ edge \,}{ cases, {here} \\\\\} {}} some }{,{\\ edge \,}{ cases, {here} \\\\\} Other tasks related to string operations: Metrics Array length String length Copy a string Empty string  (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff  (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet   Brace_expansion_using_ranges
#Visual_Basic_.NET
Visual Basic .NET
Module Module1   Function GetGroup(s As String, depth As Integer) As Tuple(Of List(Of String), String) Dim out As New List(Of String) Dim comma = False While Not String.IsNullOrEmpty(s) Dim gs = GetItem(s, depth) Dim g = gs.Item1 s = gs.Item2 If String.IsNullOrEmpty(s) Then Exit While End If out.AddRange(g)   If s(0) = "}" Then If comma Then Return Tuple.Create(out, s.Substring(1)) End If Return Tuple.Create(out.Select(Function(a) "{" + a + "}").ToList(), s.Substring(1)) End If   If s(0) = "," Then comma = True s = s.Substring(1) End If End While Return Nothing End Function   Function GetItem(s As String, Optional depth As Integer = 0) As Tuple(Of List(Of String), String) Dim out As New List(Of String) From {""} While Not String.IsNullOrEmpty(s) Dim c = s(0) If depth > 0 AndAlso (c = "," OrElse c = "}") Then Return Tuple.Create(out, s) End If If c = "{" Then Dim x = GetGroup(s.Substring(1), depth + 1) If Not IsNothing(x) Then Dim tout As New List(Of String) For Each a In out For Each b In x.Item1 tout.Add(a + b) Next Next out = tout s = x.Item2 Continue While End If End If If c = "\" AndAlso s.Length > 1 Then c += s(1) s = s.Substring(1) End If out = out.Select(Function(a) a + c).ToList() s = s.Substring(1) End While Return Tuple.Create(out, s) End Function   Sub Main() For Each s In { "It{{em,alic}iz,erat}e{d,}, please.", "~/{Downloads,Pictures}/*.{jpg,gif,png}", "{,{,gotta have{ ,\, again\, }}more }cowbell!", "{}} some }{,{\\{ edge, edge} \,}{ cases, {here} \\\\\}" } Dim fmt = "{0}" + vbNewLine + vbTab + "{1}" Dim parts = GetItem(s) Dim res = String.Join(vbNewLine + vbTab, parts.Item1) Console.WriteLine(fmt, s, res) Next End Sub   End Module
http://rosettacode.org/wiki/Brazilian_numbers
Brazilian numbers
Brazilian numbers are so called as they were first formally presented at the 1994 math Olympiad Olimpiada Iberoamericana de Matematica in Fortaleza, Brazil. Brazilian numbers are defined as: The set of positive integer numbers where each number N has at least one natural number B where 1 < B < N-1 where the representation of N in base B has all equal digits. E.G. 1, 2 & 3 can not be Brazilian; there is no base B that satisfies the condition 1 < B < N-1. 4 is not Brazilian; 4 in base 2 is 100. The digits are not all the same. 5 is not Brazilian; 5 in base 2 is 101, in base 3 is 12. There is no representation where the digits are the same. 6 is not Brazilian; 6 in base 2 is 110, in base 3 is 20, in base 4 is 12. There is no representation where the digits are the same. 7 is Brazilian; 7 in base 2 is 111. There is at least one representation where the digits are all the same. 8 is Brazilian; 8 in base 3 is 22. There is at least one representation where the digits are all the same. and so on... All even integers 2P >= 8 are Brazilian because 2P = 2(P-1) + 2, which is 22 in base P-1 when P-1 > 2. That becomes true when P >= 4. More common: for all all integers R and S, where R > 1 and also S-1 > R, then R*S is Brazilian because R*S = R(S-1) + R, which is RR in base S-1 The only problematic numbers are squares of primes, where R = S. Only 11^2 is brazilian to base 3. All prime integers, that are brazilian, can only have the digit 1. Otherwise one could factor out the digit, therefore it cannot be a prime number. Mostly in form of 111 to base Integer(sqrt(prime number)). Must be an odd count of 1 to stay odd like primes > 2 Task Write a routine (function, whatever) to determine if a number is Brazilian and use the routine to show here, on this page; the first 20 Brazilian numbers; the first 20 odd Brazilian numbers; the first 20 prime Brazilian numbers; See also OEIS:A125134 - Brazilian numbers OEIS:A257521 - Odd Brazilian numbers OEIS:A085104 - Prime Brazilian numbers
#Racket
Racket
#lang racket   (require math/number-theory)   (define (repeat-digit? n base d-must-be-1?) (call-with-values (λ () (quotient/remainder n base)) (λ (q d) (and (or (not d-must-be-1?) (= d 1)) (let loop ((n q)) (if (zero? n) d (call-with-values (λ () (quotient/remainder n base)) (λ (q r) (and (= d r) (loop q))))))))))   (define (brazilian? n (for-prime? #f)) (for/first ((b (in-range 2 (sub1 n))) #:when (repeat-digit? n b for-prime?)) b))   (define (prime-brazilian? n) (and (prime? n) (brazilian? n #t)))   (module+ main (displayln "First 20 Brazilian numbers:") (stream->list (stream-take (stream-filter brazilian? (in-naturals)) 20)) (displayln "First 20 odd Brazilian numbers:") (stream->list (stream-take (stream-filter brazilian? (stream-filter odd? (in-naturals))) 20)) (displayln "First 20 prime Brazilian numbers:") (stream->list (stream-take (stream-filter prime-brazilian? (stream-filter odd? (in-naturals))) 20)))
http://rosettacode.org/wiki/Calendar
Calendar
Create a routine that will generate a text calendar for any year. Test the calendar by generating a calendar for the year 1969, on a device of the time. Choose one of the following devices: A line printer with a width of 132 characters. An IBM 3278 model 4 terminal (80×43 display with accented characters). Target formatting the months of the year to fit nicely across the 80 character width screen. Restrict number of lines in test output to 43. (Ideally, the program will generate well-formatted calendars for any page width from 20 characters up.) Kudos (κῦδος) for routines that also transition from Julian to Gregorian calendar. This task is inspired by Real Programmers Don't Use PASCAL by Ed Post, Datamation, volume 29 number 7, July 1983. THE REAL PROGRAMMER'S NATURAL HABITAT "Taped to the wall is a line-printer Snoopy calender for the year 1969." For further Kudos see task CALENDAR, where all code is to be in UPPERCASE. For economy of size, do not actually include Snoopy generation in either the code or the output, instead just output a place-holder. Related task   Five weekends
#M2000_Interpreter
M2000 Interpreter
  Module Calendar (Year, LocaleId) { Function GetMax(Year, Month) { a=date(str$(Year)+"-"+str$(Month)+"-1") max=32 do { max-- m=val(str$(cdate(a,0,0,max), "m")) } until m=Month =max+1 } Function SkipMo(Year, Month) { a=date(str$(Year)+"-"+str$(Month)+"-1") =(val(str$(a, "w"))-8) mod 7 +7 } Function Title$(a$) { =Ucase$(left$(a$,1))+Lcase$(Mid$(a$, 2)) } locale LocaleId Cursor 0,Height-1 ' last line, so each new line scroll all lines up Print Over $(2), Year Print For j=0 to 3 { Print For i=1 to 3 { Month=i+j*3 Print Part @((i-1)*29-1), $(2,22), Title$(Ucase$(locale$(55+Month))) } Print Dim Skip(1 to 3), Count(1 to 3), D(1 to 3)=1 For i=1 to 3 { Month=i+j*3 if i>1 Then Print String$(" ",8); For k=42 to 48 :Print Title$(Ucase$(Left$(locale$(k),2)));" ";:Next k Skip(i)=SkipMo(Year, Month) Count(i)=GetMax(Year, Month) } Print For i=1 to 3 { if i>1 Then Print String$(" ",8); For k=1 to 7 { skip(i)-- if skip(i)>0 Then Print " "; :continue Count(i)-- Print format$("{0::-2} ", d(i)); d(i)++ } } Print Print @(0) For m=1 to 5 { For i=1 to 3 { if i>1 Then Print String$(" ",8); For k=1 to 7 { Count(i)-- if Count(i)<0 Then Print " "; : Continue Print format$("{0::-2} ", d(i)); d(i)++ } } Print } } } Form 80,43 Calendar 1969, 1033 ' English k=Key$ ' wait key Calendar 2018, 1032 ' Greek  
http://rosettacode.org/wiki/Brownian_tree
Brownian tree
Brownian tree You are encouraged to solve this task according to the task description, using any language you may know. Task Generate and draw a   Brownian Tree. A Brownian Tree is generated as a result of an initial seed, followed by the interaction of two processes. The initial "seed" is placed somewhere within the field. Where is not particularly important; it could be randomized, or it could be a fixed point. Particles are injected into the field, and are individually given a (typically random) motion pattern. When a particle collides with the seed or tree, its position is fixed, and it's considered to be part of the tree. Because of the lax rules governing the random nature of the particle's placement and motion, no two resulting trees are really expected to be the same, or even necessarily have the same general shape.
#Processing
Processing
boolean SIDESTICK = false; boolean[][] isTaken;   void setup() { size(512, 512); background(0); isTaken = new boolean[width][height]; isTaken[width/2][height/2] = true; }   void draw() { int x = floor(random(width)); int y = floor(random(height)); if (isTaken[x][y]) { return; } while (true) { int xp = x + floor(random(-1, 2)); int yp = y + floor(random(-1, 2)); boolean iscontained = ( 0 <= xp && xp < width && 0 <= yp && yp < height ); if (iscontained && !isTaken[xp][yp]) { x = xp; y = yp; continue; } else { if (SIDESTICK || (iscontained && isTaken[xp][yp])) { isTaken[x][y] = true; set(x, y, #FFFFFF); } break; } } if (frameCount > width * height) { noLoop(); } }
http://rosettacode.org/wiki/Bulls_and_cows
Bulls and cows
Bulls and Cows Task Create a four digit random number from the digits   1   to   9,   without duplication. The program should:   ask for guesses to this number   reject guesses that are malformed   print the score for the guess The score is computed as: The player wins if the guess is the same as the randomly chosen number, and the program ends. A score of one bull is accumulated for each digit in the guess that equals the corresponding digit in the randomly chosen initial number. A score of one cow is accumulated for each digit in the guess that also appears in the randomly chosen number, but in the wrong position. Related tasks   Bulls and cows/Player   Guess the number   Guess the number/With Feedback   Mastermind
#Frink
Frink
  // Bulls and Cows - Written in Frink println["Welcome to Bulls and Cows!"]   // Put 4 random digits into target array digits = array[1 to 9] target = new array for i = 0 to 3 { target@i = digits.removeRandom[] }   // Game variables guessCount = 0 solved = 0   while solved == 0 { // Round variables bulls = 0 cows = 0   // Input guess from player guess = input["Guess a 4 digit number with numbers 1 to 9: "]   // Valid Guess Tests. Set validGuess to 1. If any test fails it will be set to 0 validGuess = 1 // Test for exactly 4 digits if length[guess] != 4 { println["$guess is invalid. Your guess must be 4 digits."] validGuess = 0 } // Test for any characters not in 1 - 9 using regex if guess =~ %r/[^1-9]/ { println["$guess is invalid. Your guess can only contain the digits 1 through 9."] validGuess = 0 } // Check for duplicate digits in guess comboCheck = 1 guessArr = charList[guess] // Split guess string into array of characters. guessArrCombos = guessArr.combinations[2] // Divide the array into all possible 2 digits combinations. for geussCombo = guessArrCombos { if geussCombo@0 == geussCombo@1 // If the two digits in the combinations are the same mark the comboCheck as failed. comboCheck = 0 } if comboCheck == 0 { println["$guess is invalid. Each digit in your guess should be unique."] validGuess = 0 }   // If all tests pass, continue with the game. if validGuess == 1 { guessCount = guessCount + 1 for i = 0 to 3 { if parseInt[guessArr@i] == target@i // Convert guess from string to int. Frink imports all input as strings. { bulls = bulls + 1 next // If bull is found, skip the contains check. } if target.contains[parseInt[guessArr@i]] { cows = cows + 1 } } if bulls == 4 { solved = 1 // Exit from While loop. } else { // Print the results of the guess. Formatting for plurals. bullsPlural = bulls == 1 ? "bull" : "bulls" cowsPlural = cows == 1 ? "cow" : "cows" println["Your guess of $guess had $bulls $bullsPlural and $cows $cowsPlural."] } } } guessPlural = guessCount == 1 ? "guess" : "guesses" println["Congratulations! Your guess of $guess was correct! You solved this in $guessCount $guessPlural."]  
http://rosettacode.org/wiki/Caesar_cipher
Caesar cipher
Task Implement a Caesar cipher, both encoding and decoding. The key is an integer from 1 to 25. This cipher rotates (either towards left or right) the letters of the alphabet (A to Z). The encoding replaces each letter with the 1st to 25th next letter in the alphabet (wrapping Z to A). So key 2 encrypts "HI" to "JK", but key 20 encrypts "HI" to "BC". This simple "mono-alphabetic substitution cipher" provides almost no security, because an attacker who has the encoded message can either use frequency analysis to guess the key, or just try all 25 keys. Caesar cipher is identical to Vigenère cipher with a key of length 1. Also, Rot-13 is identical to Caesar cipher with key 13. Related tasks Rot-13 Substitution Cipher Vigenère Cipher/Cryptanalysis
#Elixir
Elixir
defmodule Caesar_cipher do defp set_map(map, range, key) do org = Enum.map(range, &List.to_string [&1]) {a, b} = Enum.split(org, key) Enum.zip(org, b ++ a) |> Enum.into(map) end   def encode(text, key) do map = Map.new |> set_map(?a..?z, key) |> set_map(?A..?Z, key) String.graphemes(text) |> Enum.map_join(fn c -> Map.get(map, c, c) end) end end   text = "The five boxing wizards jump quickly" key = 3 IO.puts "Original: #{text}" IO.puts "Encrypted: #{enc = Caesar_cipher.encode(text, key)}" IO.puts "Decrypted: #{Caesar_cipher.encode(enc, -key)}"
http://rosettacode.org/wiki/Calculating_the_value_of_e
Calculating the value of e
Task Calculate the value of   e. (e   is also known as   Euler's number   and   Napier's constant.) See details: Calculating the value of e
#Standard_ML
Standard ML
fun calcEToEps() = let val eps = 1.0e~15 fun calcToEps'(eest: real, prev: real, denom, i) = if Real.abs(eest - prev) < eps then eest else let val denom' = denom * i; val prev' = eest in calcToEps'(eest + 1.0/denom', prev', denom', i + 1.0) end in calcToEps'(2.0, 1.0, 1.0, 2.0) end;
http://rosettacode.org/wiki/Calculating_the_value_of_e
Calculating the value of e
Task Calculate the value of   e. (e   is also known as   Euler's number   and   Napier's constant.) See details: Calculating the value of e
#Swift
Swift
import Foundation     func calculateE(epsilon: Double = 1.0e-15) -> Double { var fact: UInt64 = 1 var e = 2.0, e0 = 0.0 var n = 2   repeat { e0 = e fact *= UInt64(n) n += 1 e += 1.0 / Double(fact) } while fabs(e - e0) >= epsilon   return e }   print(String(format: "e = %.15f\n", arguments: [calculateE()]))
http://rosettacode.org/wiki/Call_a_function
Call a function
Task Demonstrate the different syntax and semantics provided for calling a function. This may include:   Calling a function that requires no arguments   Calling a function with a fixed number of arguments   Calling a function with optional arguments   Calling a function with a variable number of arguments   Calling a function with named arguments   Using a function in statement context   Using a function in first-class context within an expression   Obtaining the return value of a function   Distinguishing built-in functions and user-defined functions   Distinguishing subroutines and functions   Stating whether arguments are passed by value or by reference   Is partial application possible and how This task is not about defining functions.
#Kotlin
Kotlin
// version 1.0.6   fun fun1() = println("No arguments")   fun fun2(i: Int) = println("One argument = $i")   fun fun3(i: Int, j: Int = 0) = println("One required argument = $i, one optional argument = $j")   fun fun4(vararg v: Int) = println("Variable number of arguments = ${v.asList()}")   fun fun5(i: Int) = i * i   fun fun6(i: Int, f: (Int) -> Int) = f(i)   fun fun7(i: Int): Double = i / 2.0   fun fun8(x: String) = { y: String -> x + " " + y }   fun main(args: Array<String>) { fun1() // no arguments fun2(2) // fixed number of arguments, one here fun3(3) // optional argument, default value used here fun4(4, 5, 6) // variable number of arguments fun3(j = 8, i = 7) // using named arguments, order unimportant val b = false if (b) fun1() else fun2(9) // statement context println(1 + fun6(4, ::fun5) + 3) // first class context within an expression println(fun5(5)) // obtaining return value println(Math.round(2.5)) // no distinction between built-in and user-defined functions, though former usually have a receiver fun1() // calling sub-routine which has a Unit return type by default println(fun7(11)) // calling function with a return type of Double (here explicit but can be implicit) println(fun8("Hello")("world")) // partial application isn't supported though you can do this }
http://rosettacode.org/wiki/Catalan_numbers
Catalan numbers
Catalan numbers You are encouraged to solve this task according to the task description, using any language you may know. Catalan numbers are a sequence of numbers which can be defined directly: C n = 1 n + 1 ( 2 n n ) = ( 2 n ) ! ( n + 1 ) ! n !  for  n ≥ 0. {\displaystyle C_{n}={\frac {1}{n+1}}{2n \choose n}={\frac {(2n)!}{(n+1)!\,n!}}\qquad {\mbox{ for }}n\geq 0.} Or recursively: C 0 = 1 and C n + 1 = ∑ i = 0 n C i C n − i for  n ≥ 0 ; {\displaystyle C_{0}=1\quad {\mbox{and}}\quad C_{n+1}=\sum _{i=0}^{n}C_{i}\,C_{n-i}\quad {\text{for }}n\geq 0;} Or alternatively (also recursive): C 0 = 1 and C n = 2 ( 2 n − 1 ) n + 1 C n − 1 , {\displaystyle C_{0}=1\quad {\mbox{and}}\quad C_{n}={\frac {2(2n-1)}{n+1}}C_{n-1},} Task Implement at least one of these algorithms and print out the first 15 Catalan numbers with each. Memoization   is not required, but may be worth the effort when using the second method above. Related tasks Catalan numbers/Pascal's triangle Evaluate binomial coefficients
#Pascal
Pascal
Program CatalanNumbers(output);   function catalanNumber1(n: integer): double; begin if n = 0 then catalanNumber1 := 1.0 else catalanNumber1 := double(4 * n - 2) / double(n + 1) * catalanNumber1(n-1); end;   var number: integer;   begin writeln('Catalan Numbers'); writeln('Recursion with a fraction:'); for number := 0 to 14 do writeln (number:3, round(catalanNumber1(number)):9); end.
http://rosettacode.org/wiki/Brace_expansion
Brace expansion
Brace expansion is a type of parameter expansion made popular by Unix shells, where it allows users to specify multiple similar string parameters without having to type them all out. E.g. the parameter enable_{audio,video} would be interpreted as if both enable_audio and enable_video had been specified. Task[edit] Write a function that can perform brace expansion on any input string, according to the following specification. Demonstrate how it would be used, and that it passes the four test cases given below. Specification In the input string, balanced pairs of braces containing comma-separated substrings (details below) represent alternations that specify multiple alternatives which are to appear at that position in the output. In general, one can imagine the information conveyed by the input string as a tree of nested alternations interspersed with literal substrings, as shown in the middle part of the following diagram: It{{em,alic}iz,erat}e{d,} parse  ―――――▶ ‌ It ⎧ ⎨ ⎩ ⎧ ⎨ ⎩ em ⎫ ⎬ ⎭ alic iz ⎫ ⎬ ⎭ erat e ⎧ ⎨ ⎩ d ⎫ ⎬ ⎭ ‌ expand  ―――――▶ ‌ Itemized Itemize Italicized Italicize Iterated Iterate input string alternation tree output (list of strings) This tree can in turn be transformed into the intended list of output strings by, colloquially speaking, determining all the possible ways to walk through it from left to right while only descending into one branch of each alternation one comes across (see the right part of the diagram). When implementing it, one can of course combine the parsing and expansion into a single algorithm, but this specification discusses them separately for the sake of clarity. Expansion of alternations can be more rigorously described by these rules: a ⎧ ⎨ ⎩ 2 ⎫ ⎬ ⎭ 1 b ⎧ ⎨ ⎩ X ⎫ ⎬ ⎭ Y X c ⟶ a2bXc a2bYc a2bXc a1bXc a1bYc a1bXc An alternation causes the list of alternatives that will be produced by its parent branch to be increased 𝑛-fold, each copy featuring one of the 𝑛 alternatives produced by the alternation's child branches, in turn, at that position. This means that multiple alternations inside the same branch are cumulative  (i.e. the complete list of alternatives produced by a branch is the string-concatenating "Cartesian product" of its parts). All alternatives (even duplicate and empty ones) are preserved, and they are ordered like the examples demonstrate  (i.e. "lexicographically" with regard to the alternations). The alternatives produced by the root branch constitute the final output. Parsing the input string involves some additional complexity to deal with escaped characters and "incomplete" brace pairs: a\\{\\\{b,c\,d} ⟶ a\\ ⎧ ⎨ ⎩ \\\{b ⎫ ⎬ ⎭ c\,d {a,b{c{,{d}}e}f ⟶ {a,b{c ⎧ ⎨ ⎩ ‌ ⎫ ⎬ ⎭ {d} e}f An unescaped backslash which precedes another character, escapes that character (to force it to be treated as literal). The backslashes are passed along to the output unchanged. Balanced brace pairs are identified by, conceptually, going through the string from left to right and associating each unescaped closing brace that is encountered with the nearest still unassociated unescaped opening brace to its left (if any). Furthermore, each unescaped comma is associated with the innermost brace pair that contains it (if any). With that in mind: Each brace pair that has at least one comma associated with it, forms an alternation (whose branches are the brace pair's contents split at its commas). The associated brace and comma characters themselves do not become part of the output. Brace characters from pairs without any associated comma, as well as unassociated brace and comma characters, as well as all characters that are not covered by the preceding rules, are instead treated as literals. For every possible input string, your implementation should produce exactly the output which this specification mandates. Please comply with this even when it's inconvenient, to ensure that all implementations are comparable. However, none of the above should be interpreted as instructions (or even recommendations) for how to implement it. Try to come up with a solution that is idiomatic in your programming language. (See #Perl for a reference implementation.) Test Cases Input (single string) Ouput (list/array of strings) ~/{Downloads,Pictures}/*.{jpg,gif,png} ~/Downloads/*.jpg ~/Downloads/*.gif ~/Downloads/*.png ~/Pictures/*.jpg ~/Pictures/*.gif ~/Pictures/*.png It{{em,alic}iz,erat}e{d,}, please. Itemized, please. Itemize, please. Italicized, please. Italicize, please. Iterated, please. Iterate, please. {,{,gotta have{ ,\, again\, }}more }cowbell! cowbell! more cowbell! gotta have more cowbell! gotta have\, again\, more cowbell! {}} some }{,{\\{ edge, edge} \,}{ cases, {here} \\\\\} {}} some }{,{\\ edge \,}{ cases, {here} \\\\\} {}} some }{,{\\ edge \,}{ cases, {here} \\\\\} Other tasks related to string operations: Metrics Array length String length Copy a string Empty string  (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff  (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet   Brace_expansion_using_ranges
#Wren
Wren
var getGroup // forward declaration   var getItem = Fn.new { |s, depth| var out = [""] while (s != "") { var c = s[0] if (depth > 0 && (c == "," || c == "}")) return [out, s] var cont = false if (c == "{") { var x = getGroup.call(s[1..-1], depth+1) if (!x[0].isEmpty) { var t = [] for (a in out) { for (b in x[0]) { t.add(a + b) } } out = t s = x[1] cont = true } } if (!cont) { if (c == "\\" && s.count > 1) { c = c + s[1] s = s[1..-1] } out = out.map { |a| a + c }.toList s = s[1..-1] } } return [out, s] }   getGroup = Fn.new { |s, depth| var out = [] var comma = false while (s != "") { var t = getItem.call(s, depth) var g = t[0] s = t[1] if (s == "") break out.addAll(g) if (s[0] == "}") { if (comma) return [out, s[1..-1]] return [out.map { |a| "{" + a + "}" }.toList, s[1..-1]] } if (s[0] == ",") { comma = true s = s[1..-1] } } return [[], ""] }   var inputs = [ "~/{Downloads,Pictures}/*.{jpg,gif,png}", "It{{em,alic}iz,erat}e{d,}, please.", "{,{,gotta have{ ,\\, again\\, }}more }cowbell!", "{}} some }{,{\\\\{ edge, edge} \\,}{ cases, {here} \\\\\\\\\\}" ] for (input in inputs) { System.print(input) for (s in getItem.call(input, 0)[0]) System.print(" " + s) System.print() }
http://rosettacode.org/wiki/Brazilian_numbers
Brazilian numbers
Brazilian numbers are so called as they were first formally presented at the 1994 math Olympiad Olimpiada Iberoamericana de Matematica in Fortaleza, Brazil. Brazilian numbers are defined as: The set of positive integer numbers where each number N has at least one natural number B where 1 < B < N-1 where the representation of N in base B has all equal digits. E.G. 1, 2 & 3 can not be Brazilian; there is no base B that satisfies the condition 1 < B < N-1. 4 is not Brazilian; 4 in base 2 is 100. The digits are not all the same. 5 is not Brazilian; 5 in base 2 is 101, in base 3 is 12. There is no representation where the digits are the same. 6 is not Brazilian; 6 in base 2 is 110, in base 3 is 20, in base 4 is 12. There is no representation where the digits are the same. 7 is Brazilian; 7 in base 2 is 111. There is at least one representation where the digits are all the same. 8 is Brazilian; 8 in base 3 is 22. There is at least one representation where the digits are all the same. and so on... All even integers 2P >= 8 are Brazilian because 2P = 2(P-1) + 2, which is 22 in base P-1 when P-1 > 2. That becomes true when P >= 4. More common: for all all integers R and S, where R > 1 and also S-1 > R, then R*S is Brazilian because R*S = R(S-1) + R, which is RR in base S-1 The only problematic numbers are squares of primes, where R = S. Only 11^2 is brazilian to base 3. All prime integers, that are brazilian, can only have the digit 1. Otherwise one could factor out the digit, therefore it cannot be a prime number. Mostly in form of 111 to base Integer(sqrt(prime number)). Must be an odd count of 1 to stay odd like primes > 2 Task Write a routine (function, whatever) to determine if a number is Brazilian and use the routine to show here, on this page; the first 20 Brazilian numbers; the first 20 odd Brazilian numbers; the first 20 prime Brazilian numbers; See also OEIS:A125134 - Brazilian numbers OEIS:A257521 - Odd Brazilian numbers OEIS:A085104 - Prime Brazilian numbers
#Raku
Raku
multi is-Brazilian (Int $n where $n %% 2 && $n > 6) { True }   multi is-Brazilian (Int $n) { LOOP: loop (my int $base = 2; $base < $n - 1; ++$base) { my $digit; for $n.polymod( $base xx * ) { $digit //= $_; next LOOP if $digit != $_; } return True } False }   my $upto = 20;   put "First $upto Brazilian numbers:\n", (^Inf).hyper.grep( &is-Brazilian )[^$upto];   put "\nFirst $upto odd Brazilian numbers:\n", (^Inf).hyper.map( * * 2 + 1 ).grep( &is-Brazilian )[^$upto];   put "\nFirst $upto prime Brazilian numbers:\n", (^Inf).hyper(:8degree).grep( { .is-prime && .&is-Brazilian } )[^$upto];
http://rosettacode.org/wiki/Calendar
Calendar
Create a routine that will generate a text calendar for any year. Test the calendar by generating a calendar for the year 1969, on a device of the time. Choose one of the following devices: A line printer with a width of 132 characters. An IBM 3278 model 4 terminal (80×43 display with accented characters). Target formatting the months of the year to fit nicely across the 80 character width screen. Restrict number of lines in test output to 43. (Ideally, the program will generate well-formatted calendars for any page width from 20 characters up.) Kudos (κῦδος) for routines that also transition from Julian to Gregorian calendar. This task is inspired by Real Programmers Don't Use PASCAL by Ed Post, Datamation, volume 29 number 7, July 1983. THE REAL PROGRAMMER'S NATURAL HABITAT "Taped to the wall is a line-printer Snoopy calender for the year 1969." For further Kudos see task CALENDAR, where all code is to be in UPPERCASE. For economy of size, do not actually include Snoopy generation in either the code or the output, instead just output a place-holder. Related task   Five weekends
#Mathematica.2FWolfram_Language
Mathematica/Wolfram Language
DataGrid[ rowHeights:{__Integer}, colWidths:{__Integer}, spacings:{_Integer,_Integer}, borderWidths:{{_Integer,_Integer},{_Integer,_Integer}}, options_Association, data:{__List?MatrixQ}]:= With[ (*Need to make sure we have sensible defaults for the decoration options.*) {alignment=Lookup[options,"alignment",{0,0}], background=Lookup[options,"background"," "], dividers=Lookup[options,"dividers",{" "," "," "}], border=Lookup[options,"border"," "], dims={Length[rowHeights],Length[colWidths]}}, (*Pad the data so that it will fit into the specified rectangle (list of lists).*) With[{augmentedData=PadRight[data,Times@@dims,{{{background}}}]}, (*Create a matrix of dimensions based on desired rectangle. Once we have a matrix of cells we can "thread" these two matrices and use that data to coerce each cell into its final dimensions.*) With[{cellDims=ArrayReshape[Outer[List,rowHeights,colWidths],{Times@@dims,2}]}, (*MatrixAlign, defined below, rescales and aligns each cell's data.*) With[{undecoratedGrid=Partition[MapThread[MatrixAlign[alignment,#1,background][#2]&, {cellDims,augmentedData}],dims[[2]]]}, (*Add the spacing to each row.*) With[{dividedRows=MapThread[Transpose[Riffle[#2,{ConstantArray[dividers[[2]],{#1,spacings[[2]]}]},{2,-2,2}]]&, {rowHeights,undecoratedGrid}]}, (*Add the spacing between rows.*) With[{dividedColumn=Riffle[dividedRows,{Transpose[Riffle[ConstantArray[dividers[[1]],{spacings[[1]],#}]&/@colWidths,{ConstantArray[dividers[[3]],spacings]},{2,-2,2}]]},{2,-2,2}]}, (*Assemble all cell rows into actual character rows. We now have one large matrix.*) With[{dividedGrid=Catenate[Map[Flatten,dividedColumn,{2}]]}, (*Add borders.*) ArrayPad[dividedGrid,borderWidths,border]]]]]]]];   DataGrid[dims:{_Integer,_Integer},spacings_,borderWidths_,options_,data:{__List?MatrixQ}]:= (*Calculate the max height for each row and max width for each column, and then just call the previous DataGrid function above.*) With[ {rowHeights=Flatten@BlockMap[Max[Part[#,All,All,1]]&,ArrayReshape[Dimensions/@data,Append[dims,2],1],{1,dims[[2]]}], colWidths=Flatten@BlockMap[Max[Part[#,All,All,2]]&,ArrayReshape[Dimensions/@data,Append[dims,2],1],{dims[[1]],1}]}, DataGrid[rowHeights,colWidths,spacings,borderWidths,options,data]];   (*This could probably be simplified, but I like having all of the aligment options explicit and separate for testability.*) MatrixAlign[{-1,-1},dims_,pad_]:=PadRight[#,dims,pad]&; MatrixAlign[{-1,0},dims_,pad_]:=PadRight[CenterArray[#,{Dimensions[#][[1]],dims[[2]]},pad],dims,pad]&; MatrixAlign[{-1,1},dims_,pad_]:=PadRight[PadLeft[#,{Dimensions[#][[1]],dims[[2]]},pad],dims,pad]&; MatrixAlign[{0,-1},dims_,pad_]:=CenterArray[PadRight[#,{Dimensions[#][[1]],dims[[2]]},pad],dims,pad]&; MatrixAlign[{0,0},dims_,pad_]:=CenterArray[#,dims,pad]&; MatrixAlign[{0,1},dims_,pad_]:=CenterArray[PadLeft[#,{Dimensions[#][[1]],dims[[2]]},pad],dims,pad]&; MatrixAlign[{1,-1},dims_,pad_]:=PadLeft[PadRight[#,{Dimensions[#][[1]],dims[[2]]},pad],dims,pad]&; MatrixAlign[{1,0},dims_,pad_]:=PadLeft[CenterArray[#,{Dimensions[#][[1]],dims[[2]]},pad],dims,pad]&; MatrixAlign[{1,1},dims_,pad_]:=PadLeft[#,dims,pad]&;   (*While the grid functions make no assumptions about the format of the data, we will be using them with string/character data, and we will eventually want to output a calendar as a single large string. AsString gives us a standard method for transforming a matrix of characters into a string with rows delimited by newlines.*) AsString[matrix_List?MatrixQ]:=StringRiffle[matrix,"\n",""];
http://rosettacode.org/wiki/Brownian_tree
Brownian tree
Brownian tree You are encouraged to solve this task according to the task description, using any language you may know. Task Generate and draw a   Brownian Tree. A Brownian Tree is generated as a result of an initial seed, followed by the interaction of two processes. The initial "seed" is placed somewhere within the field. Where is not particularly important; it could be randomized, or it could be a fixed point. Particles are injected into the field, and are individually given a (typically random) motion pattern. When a particle collides with the seed or tree, its position is fixed, and it's considered to be part of the tree. Because of the lax rules governing the random nature of the particle's placement and motion, no two resulting trees are really expected to be the same, or even necessarily have the same general shape.
#PureBasic
PureBasic
#Window1 = 0 #Image1 = 0 #ImgGadget = 0   #NUM_PARTICLES = 3000 #width = 200 #height = 200 #xmax = #width -3 #ymax = #height -3 Define.i Event ,i ,x,y   If OpenWindow(#Window1, 0, 0, #width, #height, "Brownian Tree PureBasic Example", #PB_Window_SystemMenu ) If CreateImage(#Image1, #width, #height) ImageGadget(#ImgGadget, 0, 0, #width, #height, ImageID(#Image1)) StartDrawing(ImageOutput(#Image1)) FrontColor($FFFFFF) Plot( Random(#xmax) , Random(#ymax )) StopDrawing() SetGadgetState(#ImgGadget, ImageID(#Image1)) For i = 1 To #NUM_PARTICLES x = Random(#xmax)+1 : y = Random (#ymax)+1 StartDrawing(ImageOutput(#Image1)) While Point(x+1, y+1) + Point(x, y+1)+Point(x+1, y)+Point(x-1, y-1)+Point(x-1, y)+Point(x, y-1) = 0 x = x + (Random(2)-1) : y = y + (Random(2)-1) If x < 1 Or x > #xmax Or y < 1 Or y > #ymax x = Random(#xmax)+1 : y = Random (#ymax)+1 EndIf Wend Plot(x,y) StopDrawing() SetGadgetState(#ImgGadget, ImageID(#Image1)) Next   EndIf   Repeat Event = WaitWindowEvent() Until Event = #PB_Event_CloseWindow EndIf
http://rosettacode.org/wiki/Bulls_and_cows
Bulls and cows
Bulls and Cows Task Create a four digit random number from the digits   1   to   9,   without duplication. The program should:   ask for guesses to this number   reject guesses that are malformed   print the score for the guess The score is computed as: The player wins if the guess is the same as the randomly chosen number, and the program ends. A score of one bull is accumulated for each digit in the guess that equals the corresponding digit in the randomly chosen initial number. A score of one cow is accumulated for each digit in the guess that also appears in the randomly chosen number, but in the wrong position. Related tasks   Bulls and cows/Player   Guess the number   Guess the number/With Feedback   Mastermind
#Go
Go
package main   import ( "bufio" "bytes" "fmt" "math/rand" "os" "strings" "time" )   func main() { fmt.Println(`Cows and Bulls Guess four digit number of unique digits in the range 1 to 9. A correct digit but not in the correct place is a cow. A correct digit in the correct place is a bull.`) // generate pattern pat := make([]byte, 4) rand.Seed(time.Now().Unix()) r := rand.Perm(9) for i := range pat { pat[i] = '1' + byte(r[i]) }   // accept and score guesses valid := []byte("123456789") guess: for in := bufio.NewReader(os.Stdin); ; { fmt.Print("Guess: ") guess, err := in.ReadString('\n') if err != nil { fmt.Println("\nSo, bye.") return } guess = strings.TrimSpace(guess) if len(guess) != 4 { // malformed: not four characters fmt.Println("Please guess a four digit number.") continue } var cows, bulls int for ig, cg := range guess { if strings.IndexRune(guess[:ig], cg) >= 0 { // malformed: repeated digit fmt.Printf("Repeated digit: %c\n", cg) continue guess } switch bytes.IndexByte(pat, byte(cg)) { case -1: if bytes.IndexByte(valid, byte(cg)) == -1 { // malformed: not a digit fmt.Printf("Invalid digit: %c\n", cg) continue guess } default: // I just think cows should go first cows++ case ig: bulls++ } } fmt.Printf("Cows: %d, bulls: %d\n", cows, bulls) if bulls == 4 { fmt.Println("You got it.") return } } }
http://rosettacode.org/wiki/Caesar_cipher
Caesar cipher
Task Implement a Caesar cipher, both encoding and decoding. The key is an integer from 1 to 25. This cipher rotates (either towards left or right) the letters of the alphabet (A to Z). The encoding replaces each letter with the 1st to 25th next letter in the alphabet (wrapping Z to A). So key 2 encrypts "HI" to "JK", but key 20 encrypts "HI" to "BC". This simple "mono-alphabetic substitution cipher" provides almost no security, because an attacker who has the encoded message can either use frequency analysis to guess the key, or just try all 25 keys. Caesar cipher is identical to Vigenère cipher with a key of length 1. Also, Rot-13 is identical to Caesar cipher with key 13. Related tasks Rot-13 Substitution Cipher Vigenère Cipher/Cryptanalysis
#Erlang
Erlang
  %% Ceasar cypher in Erlang for the rosetta code wiki. %% Implemented by J.W. Luiten   -module(ceasar). -export([main/2]).   %% rot: rotate Char by Key places rot(Char,Key) when (Char >= $A) and (Char =< $Z) or (Char >= $a) and (Char =< $z) -> Offset = $A + Char band 32, N = Char - Offset, Offset + (N + Key) rem 26; rot(Char, _Key) -> Char.   %% key: normalize key. key(Key) when Key < 0 -> 26 + Key rem 26; key(Key) when Key > 25 -> Key rem 26; key(Key) -> Key.   main(PlainText, Key) -> Encode = key(Key), Decode = key(-Key),   io:format("Plaintext ----> ~s~n", [PlainText]),   CypherText = lists:map(fun(Char) -> rot(Char, Encode) end, PlainText), io:format("Cyphertext ---> ~s~n", [CypherText]),   PlainText = lists:map(fun(Char) -> rot(Char, Decode) end, CypherText).    
http://rosettacode.org/wiki/Calculating_the_value_of_e
Calculating the value of e
Task Calculate the value of   e. (e   is also known as   Euler's number   and   Napier's constant.) See details: Calculating the value of e
#Tcl
Tcl
  set ε 1.0e-15 set fact 1 set e 2.0 set e0 0.0 set n 2   while {[expr abs($e - $e0)] > ${ε}} { set e0 $e set fact [expr $fact * $n] incr n set e [expr $e + 1.0/$fact] } puts "e = $e"
http://rosettacode.org/wiki/Calculating_the_value_of_e
Calculating the value of e
Task Calculate the value of   e. (e   is also known as   Euler's number   and   Napier's constant.) See details: Calculating the value of e
#TI-83_BASIC
TI-83 BASIC
0->D 2->N 2->E 1->F 1.0E-12->Z While abs(E-D)>Z F*N->F N+1->N E->D E+1/F->E End Disp E  
http://rosettacode.org/wiki/Call_a_function
Call a function
Task Demonstrate the different syntax and semantics provided for calling a function. This may include:   Calling a function that requires no arguments   Calling a function with a fixed number of arguments   Calling a function with optional arguments   Calling a function with a variable number of arguments   Calling a function with named arguments   Using a function in statement context   Using a function in first-class context within an expression   Obtaining the return value of a function   Distinguishing built-in functions and user-defined functions   Distinguishing subroutines and functions   Stating whether arguments are passed by value or by reference   Is partial application possible and how This task is not about defining functions.
#Lambdatalk
Lambdatalk
    The command   replace  :a0 :a1 ... an-1 in expression containing some occurences of :ai by v0 v1 ... vp-1   is rewritten in a prefixed parenthesized form   {{lambda {:a0 :a1 ... an-1} expression containing some occurences of :ai} v0 v1 ... vp-1}   so called IIFE (Immediately Invoked Function Expression), and defines an anonymous function containing a sequence of n arguments :ai, immediately invoked on a sequence of p values vi, and returning the expression in its body as so modified:   1) if p < n (partial application)   • the occurrences of the p first arguments are replaced in the function's body by the corresponding p given values, • a function waiting for missing n-p values is created, • and its reference is returned. • example: {{lambda {:x :y} ... :y ... :x ...} hello} -> {lambda {:y} ... :y ... hello ...} // replaces :x by hello -> LAMB_123 // the new functions's reference • called with the value world this function will return ... world ... hello ...   2) if p = n (normal application)   • the occurences of the n arguments are replaced in the function's body by the corresponding p given values, • the body is evaluated and the result is returned. • example {{lambda {:x :y} ... :y ... :x ...} hello world} -> {{lambda {:y} ... :y ... hello ...} world} // replaces :x by hello -> {{lambda {} ... world ... hello ...} } // replaces :y by world -> ... world ... hello ... // the value   3) if p > n (variadicity)   • the occurrences of the n-1 first arguments are replaced in the function's body by the corresponding n-1 given values, • the occurrences of the last argument are replaced in the body by the sequence of p-n supernumerary values, • the body is evaluated and the result is returned. • example: {{lambda {:x :y} ... :y ... :x ...} hello world good morning} -> {{lambda {:y} ... :y ... hello ...} world good morning} -> {{lambda {} ... world good morning ... hello ...}} -> ... world good morning ... hello ... // the value   More can be seen in http://lambdaway.free.fr/lambdawalks/?view=lambda  
http://rosettacode.org/wiki/Catalan_numbers
Catalan numbers
Catalan numbers You are encouraged to solve this task according to the task description, using any language you may know. Catalan numbers are a sequence of numbers which can be defined directly: C n = 1 n + 1 ( 2 n n ) = ( 2 n ) ! ( n + 1 ) ! n !  for  n ≥ 0. {\displaystyle C_{n}={\frac {1}{n+1}}{2n \choose n}={\frac {(2n)!}{(n+1)!\,n!}}\qquad {\mbox{ for }}n\geq 0.} Or recursively: C 0 = 1 and C n + 1 = ∑ i = 0 n C i C n − i for  n ≥ 0 ; {\displaystyle C_{0}=1\quad {\mbox{and}}\quad C_{n+1}=\sum _{i=0}^{n}C_{i}\,C_{n-i}\quad {\text{for }}n\geq 0;} Or alternatively (also recursive): C 0 = 1 and C n = 2 ( 2 n − 1 ) n + 1 C n − 1 , {\displaystyle C_{0}=1\quad {\mbox{and}}\quad C_{n}={\frac {2(2n-1)}{n+1}}C_{n-1},} Task Implement at least one of these algorithms and print out the first 15 Catalan numbers with each. Memoization   is not required, but may be worth the effort when using the second method above. Related tasks Catalan numbers/Pascal's triangle Evaluate binomial coefficients
#Perl
Perl
sub factorial { my $f = 1; $f *= $_ for 2 .. $_[0]; $f; } sub catalan { my $n = shift; factorial(2*$n) / factorial($n+1) / factorial($n); }   print "$_\t@{[ catalan($_) ]}\n" for 0 .. 20;
http://rosettacode.org/wiki/Brace_expansion
Brace expansion
Brace expansion is a type of parameter expansion made popular by Unix shells, where it allows users to specify multiple similar string parameters without having to type them all out. E.g. the parameter enable_{audio,video} would be interpreted as if both enable_audio and enable_video had been specified. Task[edit] Write a function that can perform brace expansion on any input string, according to the following specification. Demonstrate how it would be used, and that it passes the four test cases given below. Specification In the input string, balanced pairs of braces containing comma-separated substrings (details below) represent alternations that specify multiple alternatives which are to appear at that position in the output. In general, one can imagine the information conveyed by the input string as a tree of nested alternations interspersed with literal substrings, as shown in the middle part of the following diagram: It{{em,alic}iz,erat}e{d,} parse  ―――――▶ ‌ It ⎧ ⎨ ⎩ ⎧ ⎨ ⎩ em ⎫ ⎬ ⎭ alic iz ⎫ ⎬ ⎭ erat e ⎧ ⎨ ⎩ d ⎫ ⎬ ⎭ ‌ expand  ―――――▶ ‌ Itemized Itemize Italicized Italicize Iterated Iterate input string alternation tree output (list of strings) This tree can in turn be transformed into the intended list of output strings by, colloquially speaking, determining all the possible ways to walk through it from left to right while only descending into one branch of each alternation one comes across (see the right part of the diagram). When implementing it, one can of course combine the parsing and expansion into a single algorithm, but this specification discusses them separately for the sake of clarity. Expansion of alternations can be more rigorously described by these rules: a ⎧ ⎨ ⎩ 2 ⎫ ⎬ ⎭ 1 b ⎧ ⎨ ⎩ X ⎫ ⎬ ⎭ Y X c ⟶ a2bXc a2bYc a2bXc a1bXc a1bYc a1bXc An alternation causes the list of alternatives that will be produced by its parent branch to be increased 𝑛-fold, each copy featuring one of the 𝑛 alternatives produced by the alternation's child branches, in turn, at that position. This means that multiple alternations inside the same branch are cumulative  (i.e. the complete list of alternatives produced by a branch is the string-concatenating "Cartesian product" of its parts). All alternatives (even duplicate and empty ones) are preserved, and they are ordered like the examples demonstrate  (i.e. "lexicographically" with regard to the alternations). The alternatives produced by the root branch constitute the final output. Parsing the input string involves some additional complexity to deal with escaped characters and "incomplete" brace pairs: a\\{\\\{b,c\,d} ⟶ a\\ ⎧ ⎨ ⎩ \\\{b ⎫ ⎬ ⎭ c\,d {a,b{c{,{d}}e}f ⟶ {a,b{c ⎧ ⎨ ⎩ ‌ ⎫ ⎬ ⎭ {d} e}f An unescaped backslash which precedes another character, escapes that character (to force it to be treated as literal). The backslashes are passed along to the output unchanged. Balanced brace pairs are identified by, conceptually, going through the string from left to right and associating each unescaped closing brace that is encountered with the nearest still unassociated unescaped opening brace to its left (if any). Furthermore, each unescaped comma is associated with the innermost brace pair that contains it (if any). With that in mind: Each brace pair that has at least one comma associated with it, forms an alternation (whose branches are the brace pair's contents split at its commas). The associated brace and comma characters themselves do not become part of the output. Brace characters from pairs without any associated comma, as well as unassociated brace and comma characters, as well as all characters that are not covered by the preceding rules, are instead treated as literals. For every possible input string, your implementation should produce exactly the output which this specification mandates. Please comply with this even when it's inconvenient, to ensure that all implementations are comparable. However, none of the above should be interpreted as instructions (or even recommendations) for how to implement it. Try to come up with a solution that is idiomatic in your programming language. (See #Perl for a reference implementation.) Test Cases Input (single string) Ouput (list/array of strings) ~/{Downloads,Pictures}/*.{jpg,gif,png} ~/Downloads/*.jpg ~/Downloads/*.gif ~/Downloads/*.png ~/Pictures/*.jpg ~/Pictures/*.gif ~/Pictures/*.png It{{em,alic}iz,erat}e{d,}, please. Itemized, please. Itemize, please. Italicized, please. Italicize, please. Iterated, please. Iterate, please. {,{,gotta have{ ,\, again\, }}more }cowbell! cowbell! more cowbell! gotta have more cowbell! gotta have\, again\, more cowbell! {}} some }{,{\\{ edge, edge} \,}{ cases, {here} \\\\\} {}} some }{,{\\ edge \,}{ cases, {here} \\\\\} {}} some }{,{\\ edge \,}{ cases, {here} \\\\\} Other tasks related to string operations: Metrics Array length String length Copy a string Empty string  (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff  (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet   Brace_expansion_using_ranges
#zkl
zkl
fcn eyeball(code,ps=L(),brace=False){ //-->indexes of valid braces & commas cs:=L(); foreach c in (code){ // start fresh or continue (if recursing) switch(c){ case("\\"){ __cWalker.next(); } case(",") { if(brace) cs.append(__cWalker.n); } // maybe valid case("{") { // this is real only if there is matching } and a comma n:=__cWalker.n; _,cz:=self.fcn(__cWalker,ps,True); if(cz){ ps.append(n,__cWalker.n); ps.extend(cz) } // valid {} pair } case("}"){ if(brace) return(ps,cs); } } } return(ps,False) }   fcn expando(code,strings=T("")){ reg [const] stack=List(); reg roots,cs; bs,_:=eyeball(code); foreach c in (code){ if(bs.holds(__cWalker.n)){ if (c=="{") { stack.append(cs); cs=0; roots=strings; } else if(c==",") { stack.append(strings); strings=roots; cs+=1; } else if(c=="}") { do(cs){ strings=stack.pop().extend(strings); } cs=stack.pop(); } }else if(c=="\\"){ c="\\"+__cWalker.next(); strings=strings.apply('+(c)); } else strings=strings.apply('+(c)); } strings }
http://rosettacode.org/wiki/Brazilian_numbers
Brazilian numbers
Brazilian numbers are so called as they were first formally presented at the 1994 math Olympiad Olimpiada Iberoamericana de Matematica in Fortaleza, Brazil. Brazilian numbers are defined as: The set of positive integer numbers where each number N has at least one natural number B where 1 < B < N-1 where the representation of N in base B has all equal digits. E.G. 1, 2 & 3 can not be Brazilian; there is no base B that satisfies the condition 1 < B < N-1. 4 is not Brazilian; 4 in base 2 is 100. The digits are not all the same. 5 is not Brazilian; 5 in base 2 is 101, in base 3 is 12. There is no representation where the digits are the same. 6 is not Brazilian; 6 in base 2 is 110, in base 3 is 20, in base 4 is 12. There is no representation where the digits are the same. 7 is Brazilian; 7 in base 2 is 111. There is at least one representation where the digits are all the same. 8 is Brazilian; 8 in base 3 is 22. There is at least one representation where the digits are all the same. and so on... All even integers 2P >= 8 are Brazilian because 2P = 2(P-1) + 2, which is 22 in base P-1 when P-1 > 2. That becomes true when P >= 4. More common: for all all integers R and S, where R > 1 and also S-1 > R, then R*S is Brazilian because R*S = R(S-1) + R, which is RR in base S-1 The only problematic numbers are squares of primes, where R = S. Only 11^2 is brazilian to base 3. All prime integers, that are brazilian, can only have the digit 1. Otherwise one could factor out the digit, therefore it cannot be a prime number. Mostly in form of 111 to base Integer(sqrt(prime number)). Must be an odd count of 1 to stay odd like primes > 2 Task Write a routine (function, whatever) to determine if a number is Brazilian and use the routine to show here, on this page; the first 20 Brazilian numbers; the first 20 odd Brazilian numbers; the first 20 prime Brazilian numbers; See also OEIS:A125134 - Brazilian numbers OEIS:A257521 - Odd Brazilian numbers OEIS:A085104 - Prime Brazilian numbers
#REXX
REXX
/*REXX pgm finds: 1st N Brazilian #s; odd Brazilian #s; prime Brazilian #s; ZZZth #.*/ parse arg t.1 t.2 t.3 t.4 . /*obtain optional arguments from the CL*/ if t.4=='' | t.4=="," then t.4= 0 /*special test case of Nth Brazilian #.*/ hdr.1= 'first'; hdr.2= "first odd"; hdr.3= 'first prime'; hdr.4= /*four headers.*/ #p= 0 /*#P: the number of primes (so far).*/ do c=1 for 4 /*process each of the four cases. */ if t.c=='' | t.c=="," then t.c= 20 /*check if a target is null or a comma.*/ step= 1 + (c==2) /*STEP is set to unity or two (for ODD)*/ if t.c==0 then iterate /*check to see if this case target ≡ 0.*/ $=; #= 0 /*initialize list to null; counter to 0*/ do j=1 by step until #>= t.c /*search integers for Brazilian # type.*/ prime= 0 /*signify if J may not be prime. */ if c==3 then do /*is this a "case 3" calculation? */ if \isPrime(j) then iterate /*(case 3) Not a prime? Then skip it.*/ prime= 1 /*signify if J is definately a prime.*/ end /* [↓] J≡prime will be used for speedup*/ if \isBraz(j, prime) then iterate /*Not Brazilian number? " " " */ #= # + 1 /*bump the counter of Brazilian numbers*/ if c\==4 then $= $ j /*for most cases, append J to ($) list.*/ end /*j*/ /* [↑] cases 1──►3, $ has leading blank*/ say /* [↓] use a special header for cases.*/ if c==4 then do; $= j; t.c= th(t.c); end /*for Nth Brazilian number, just use J.*/ say center(' 'hdr.c" " t.c " Brazilian number"left('s', c\==4)" ", 79, '═') say strip($) /*display a case result to the terminal*/ end /*c*/ /* [↑] cases 1──►3 have a leading blank*/ exit /*stick a fork in it, we're all done. */ /*──────────────────────────────────────────────────────────────────────────────────────*/ isBraz: procedure; parse arg x,p; if x<7 then return 0 /*Is # < seven? Nope. */ if x//2==0 then return 1 /*Is # even? Yup. _*/ if p then mx= iSqrt(x) /*X prime? Use integer √X*/ else mx= x%3 -1 /*X not known if prime. */ do b=2 for mx /*scan for base 2 ──► max*/ if sameDig(x, b) then return 1 /*it's a Brazilian number*/ end /*b*/; return 0 /*not " " " */ /*──────────────────────────────────────────────────────────────────────────────────────*/ isPrime: procedure expose @. !. #p; parse arg x '' -1 _ /*get 1st arg & last decimal dig*/ if #p==0 then do;  !.=0; y= 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 do i=1 for words(y); #p= #p+1; z=word(y,i); @.#p= z; !.z=1; end end /*#P: is the number of primes. */ if !.x then return 1; if x<61 then return 0; if x//2==0 then return 0 if x//3==0 then return 0; if _==5 then return 0; if x//7==0 then return 0 do j=5 until @.j**2>x; if x//@.j ==0 then return 0 if x//(@.j+2) ==0 then return 0 end /*j*/; #p= #p + 1; @.#p= x;  !.x= 1; return 1 /*it's a prime.*/ /*──────────────────────────────────────────────────────────────────────────────────────*/ iSqrt: procedure; parse arg x; q= 1; r= 0; do while q<=x; q= q*4; end do while q>1; q=q%4; _=x-r-q; r=r%2; if _>=0 then do;x=_;r=r+q;end;end; return r /*──────────────────────────────────────────────────────────────────────────────────────*/ sameDig: procedure; parse arg x, b; f= x // b /* // ◄── the remainder.*/ x= x  % b /*  % ◄── is integer ÷ */ do while x>0; if x//b \==f then return 0 x= x % b end /*while*/; return 1 /*it has all the same dig*/ /*──────────────────────────────────────────────────────────────────────────────────────*/ th: parse arg th; return th || word('th st nd rd', 1+(th//10)*(th//100%10\==1)*(th//10<4))
http://rosettacode.org/wiki/Calendar
Calendar
Create a routine that will generate a text calendar for any year. Test the calendar by generating a calendar for the year 1969, on a device of the time. Choose one of the following devices: A line printer with a width of 132 characters. An IBM 3278 model 4 terminal (80×43 display with accented characters). Target formatting the months of the year to fit nicely across the 80 character width screen. Restrict number of lines in test output to 43. (Ideally, the program will generate well-formatted calendars for any page width from 20 characters up.) Kudos (κῦδος) for routines that also transition from Julian to Gregorian calendar. This task is inspired by Real Programmers Don't Use PASCAL by Ed Post, Datamation, volume 29 number 7, July 1983. THE REAL PROGRAMMER'S NATURAL HABITAT "Taped to the wall is a line-printer Snoopy calender for the year 1969." For further Kudos see task CALENDAR, where all code is to be in UPPERCASE. For economy of size, do not actually include Snoopy generation in either the code or the output, instead just output a place-holder. Related task   Five weekends
#Overview
Overview
DataGrid[ rowHeights:{__Integer}, colWidths:{__Integer}, spacings:{_Integer,_Integer}, borderWidths:{{_Integer,_Integer},{_Integer,_Integer}}, options_Association, data:{__List?MatrixQ}]:= With[ (*Need to make sure we have sensible defaults for the decoration options.*) {alignment=Lookup[options,"alignment",{0,0}], background=Lookup[options,"background"," "], dividers=Lookup[options,"dividers",{" "," "," "}], border=Lookup[options,"border"," "], dims={Length[rowHeights],Length[colWidths]}}, (*Pad the data so that it will fit into the specified rectangle (list of lists).*) With[{augmentedData=PadRight[data,Times@@dims,{{{background}}}]}, (*Create a matrix of dimensions based on desired rectangle. Once we have a matrix of cells we can "thread" these two matrices and use that data to coerce each cell into its final dimensions.*) With[{cellDims=ArrayReshape[Outer[List,rowHeights,colWidths],{Times@@dims,2}]}, (*MatrixAlign, defined below, rescales and aligns each cell's data.*) With[{undecoratedGrid=Partition[MapThread[MatrixAlign[alignment,#1,background][#2]&, {cellDims,augmentedData}],dims[[2]]]}, (*Add the spacing to each row.*) With[{dividedRows=MapThread[Transpose[Riffle[#2,{ConstantArray[dividers[[2]],{#1,spacings[[2]]}]},{2,-2,2}]]&, {rowHeights,undecoratedGrid}]}, (*Add the spacing between rows.*) With[{dividedColumn=Riffle[dividedRows,{Transpose[Riffle[ConstantArray[dividers[[1]],{spacings[[1]],#}]&/@colWidths,{ConstantArray[dividers[[3]],spacings]},{2,-2,2}]]},{2,-2,2}]}, (*Assemble all cell rows into actual character rows. We now have one large matrix.*) With[{dividedGrid=Catenate[Map[Flatten,dividedColumn,{2}]]}, (*Add borders.*) ArrayPad[dividedGrid,borderWidths,border]]]]]]]];   DataGrid[dims:{_Integer,_Integer},spacings_,borderWidths_,options_,data:{__List?MatrixQ}]:= (*Calculate the max height for each row and max width for each column, and then just call the previous DataGrid function above.*) With[ {rowHeights=Flatten@BlockMap[Max[Part[#,All,All,1]]&,ArrayReshape[Dimensions/@data,Append[dims,2],1],{1,dims[[2]]}], colWidths=Flatten@BlockMap[Max[Part[#,All,All,2]]&,ArrayReshape[Dimensions/@data,Append[dims,2],1],{dims[[1]],1}]}, DataGrid[rowHeights,colWidths,spacings,borderWidths,options,data]];   (*This could probably be simplified, but I like having all of the aligment options explicit and separate for testability.*) MatrixAlign[{-1,-1},dims_,pad_]:=PadRight[#,dims,pad]&; MatrixAlign[{-1,0},dims_,pad_]:=PadRight[CenterArray[#,{Dimensions[#][[1]],dims[[2]]},pad],dims,pad]&; MatrixAlign[{-1,1},dims_,pad_]:=PadRight[PadLeft[#,{Dimensions[#][[1]],dims[[2]]},pad],dims,pad]&; MatrixAlign[{0,-1},dims_,pad_]:=CenterArray[PadRight[#,{Dimensions[#][[1]],dims[[2]]},pad],dims,pad]&; MatrixAlign[{0,0},dims_,pad_]:=CenterArray[#,dims,pad]&; MatrixAlign[{0,1},dims_,pad_]:=CenterArray[PadLeft[#,{Dimensions[#][[1]],dims[[2]]},pad],dims,pad]&; MatrixAlign[{1,-1},dims_,pad_]:=PadLeft[PadRight[#,{Dimensions[#][[1]],dims[[2]]},pad],dims,pad]&; MatrixAlign[{1,0},dims_,pad_]:=PadLeft[CenterArray[#,{Dimensions[#][[1]],dims[[2]]},pad],dims,pad]&; MatrixAlign[{1,1},dims_,pad_]:=PadLeft[#,dims,pad]&;   (*While the grid functions make no assumptions about the format of the data, we will be using them with string/character data, and we will eventually want to output a calendar as a single large string. AsString gives us a standard method for transforming a matrix of characters into a string with rows delimited by newlines.*) AsString[matrix_List?MatrixQ]:=StringRiffle[matrix,"\n",""];
http://rosettacode.org/wiki/Brownian_tree
Brownian tree
Brownian tree You are encouraged to solve this task according to the task description, using any language you may know. Task Generate and draw a   Brownian Tree. A Brownian Tree is generated as a result of an initial seed, followed by the interaction of two processes. The initial "seed" is placed somewhere within the field. Where is not particularly important; it could be randomized, or it could be a fixed point. Particles are injected into the field, and are individually given a (typically random) motion pattern. When a particle collides with the seed or tree, its position is fixed, and it's considered to be part of the tree. Because of the lax rules governing the random nature of the particle's placement and motion, no two resulting trees are really expected to be the same, or even necessarily have the same general shape.
#Python
Python
import pygame, sys, os from pygame.locals import * from random import randint pygame.init()   MAXSPEED = 15 SIZE = 3 COLOR = (45, 90, 45) WINDOWSIZE = 400 TIMETICK = 1 MAXPART = 50   freeParticles = pygame.sprite.Group() tree = pygame.sprite.Group()   window = pygame.display.set_mode((WINDOWSIZE, WINDOWSIZE)) pygame.display.set_caption("Brownian Tree")   screen = pygame.display.get_surface()     class Particle(pygame.sprite.Sprite): def __init__(self, vector, location, surface): pygame.sprite.Sprite.__init__(self) self.vector = vector self.surface = surface self.accelerate(vector) self.add(freeParticles) self.rect = pygame.Rect(location[0], location[1], SIZE, SIZE) self.surface.fill(COLOR, self.rect)   def onEdge(self): if self.rect.left <= 0: self.vector = (abs(self.vector[0]), self.vector[1]) elif self.rect.top <= 0: self.vector = (self.vector[0], abs(self.vector[1])) elif self.rect.right >= WINDOWSIZE: self.vector = (-abs(self.vector[0]), self.vector[1]) elif self.rect.bottom >= WINDOWSIZE: self.vector = (self.vector[0], -abs(self.vector[1]))   def update(self): if freeParticles in self.groups(): self.surface.fill((0,0,0), self.rect) self.remove(freeParticles) if pygame.sprite.spritecollideany(self, freeParticles): self.accelerate((randint(-MAXSPEED, MAXSPEED), randint(-MAXSPEED, MAXSPEED))) self.add(freeParticles) elif pygame.sprite.spritecollideany(self, tree): self.stop() else: self.add(freeParticles)   self.onEdge()   if (self.vector == (0,0)) and tree not in self.groups(): self.accelerate((randint(-MAXSPEED, MAXSPEED), randint(-MAXSPEED, MAXSPEED))) self.rect.move_ip(self.vector[0], self.vector[1]) self.surface.fill(COLOR, self.rect)   def stop(self): self.vector = (0,0) self.remove(freeParticles) self.add(tree)   def accelerate(self, vector): self.vector = vector   NEW = USEREVENT + 1 TICK = USEREVENT + 2   pygame.time.set_timer(NEW, 50) pygame.time.set_timer(TICK, TIMETICK)     def input(events): for event in events: if event.type == QUIT: sys.exit(0) elif event.type == NEW and (len(freeParticles) < MAXPART): Particle((randint(-MAXSPEED,MAXSPEED), randint(-MAXSPEED,MAXSPEED)), (randint(0, WINDOWSIZE), randint(0, WINDOWSIZE)), screen) elif event.type == TICK: freeParticles.update()     half = WINDOWSIZE/2 tenth = WINDOWSIZE/10   root = Particle((0,0), (randint(half-tenth, half+tenth), randint(half-tenth, half+tenth)), screen) root.stop()   while True: input(pygame.event.get()) pygame.display.flip()