Product of subset of numbers in python
Question: I'm going through project euler, and i'm getting stuck on this question.

I'm going to post my code with comments, so everyone can follow my thinking
and see where I went wrong. All suggestions are appreciated :)

    
    
    # need to find the largest product in a series
    
    import time # brings time into the code
    
    start = time.time() # creates a start time for the code
    
    list = [] # where I'm going to store the multipules
    
    # the '\ takes the grid and converts it into one long number'
    
    num = '\
    73167176531330624919225119674426574742355349194934\
    96983520312774506326239578318016984801869478851843\
    85861560789112949495459501737958331952853208805511\
    12540698747158523863050715693290963295227443043557\
    66896648950445244523161731856403098711121722383113\
    62229893423380308135336276614282806444486645238749\
    30358907296290491560440772390713810515859307960866\
    70172427121883998797908792274921901699720888093776\
    65727333001053367881220235421809751254540594752243\
    52584907711670556013604839586446706324415722155397\
    53697817977846174064955149290862569321978468622482\
    83972241375657056057490261407972968652414535100474\
    82166370484403199890008895243450658541227588666881\
    16427171479924442928230863465674813919123162824586\
    17866458359124566529476545682848912883142607690042\
    24219022671055626321111109370544217506941658960408\
    07198403850962455444362981230987879927244284909188\
    84580156166097919133875499200524063689912560717606\
    05886116467109405077541002256983155200055935729725\
    71636269561882670428252483600823257530420752963450' 
    
    i = 0 # start of the ticker
    
    for i in range(0, 1000, 1): # the length of the large block of numbers is 1000
    
        hold_num = int(num[i])*int(num[i+1])*int(num[i+2]) # im creating a number of every three consecutive numbers ... this is the subset
        list.append(hold_num) # storing the products in a list
        i =+ 1
    
    print max(list) # finding the max of the products in the stored list
    

I end up getting this error:

    
    
    Traceback (most recent call last):
      File "/Users/robertdefilippi/Documents/Python/Euler/8eu.py", line 37, in <module>
        hold_num = int(num[i])*int(num[i+1])*int(num[i+2])
    IndexError: string index out of range
    [Finished in 0.0s with exit code 1]
    

Any suggestions on what I'm doing wrong?


Answer: When you are doing `for i in range(0, 1000, 1)`, reaching 999, `num[i+1]` and
`num[i+2]` will be out range.

You have to use `range(0,998,1)` instead. Which can be shortened to
`range(998)`. And doing this, `i` will be incremented and starts at 0. You
don't need to do `i+=1` or `i=0`.

