Check if the first and last digit of the smallest number forms a prime | function to check prime ; Function to generate smallest possible number with given digits ; Declare a hash array of size 10 and initialize all the elements to zero ; store the number of occurrences of the digits in the given array into the hash table ; Traverse the hash in ascending order to print the required number ; Print the number of times a digits occurs ; extracting the first digit ; extracting the last digit ; printing the prime combinations ; Driver code
function isPrime ( n ) { var i , c = 0 ; for ( i = 1 ; i < n / 2 ; i ++ ) { if ( n % i == 0 ) c ++ ; } if ( c == 1 ) return 1 ; else return 0 ; } function findMinNum ( arr , n ) { var first = 0 , last = 0 , num , rev , i ; var hash = new Array ( 10 ) . fill ( 0 ) ; for ( var i = 0 ; i < n ; i ++ ) { hash [ arr [ i ] ] ++ ; } document . write ( " " ) ; for ( var i = 0 ; i <= 9 ; i ++ ) { for ( var j = 0 ; j < hash [ i ] ; j ++ ) document . write ( i ) ; } document . write ( " " ) ; for ( i = 0 ; i <= 9 ; i ++ ) { if ( hash [ i ] != 0 ) { first = i ; break ; } } for ( i = 9 ; i >= 0 ; i -- ) { if ( hash [ i ] != 0 ) { last = i ; break ; } } num = first * 10 + last ; rev = last * 10 + first ; document . write ( " " ) ; if ( isPrime ( num ) && isPrime ( rev ) ) document . write ( num + " " + rev ) ; else if ( isPrime ( num ) ) document . write ( num ) ; else if ( isPrime ( rev ) ) document . write ( rev ) ; else document . write ( " " ) ; } var arr = [ 1 , 2 , 4 , 7 , 8 ] ; findMinNum ( arr , 5 ) ;