text: If there exists no element no sum is possible
code: else if ( i == 0 ) subset [ i % 2 ] [ j ] = false ; else if ( arr [ i - 1 ] <= j ) subset [ i % 2 ] [ j ] = subset [ ( i + 1 ) % 2 ] [ j - arr [ i - 1 ] ] || subset [ ( i + 1 ) % 2 ] [ j ] ; else subset [ i % 2 ] [ j ] = subset [ ( i + 1 ) % 2 ] [ j ] ; } } return subset [ n % 2 ] [ sum ] ; }