text: function to return the number of solutions
code: static int countSolutions ( int a ) { int count = bitCount ( a ) ; count = ( int ) System . Math . Pow ( 2 , count ) ; return count ; } static int bitCount ( int n ) { int count = 0 ; while ( n != 0 ) { count ++ ; n &= ( n - 1 ) ; } return count ; }