if i is even that mean till now we have even number of elements so we store result in 0 th indexed row
else { while ( ++ j <= W ) { if ( wt [ i ] <= j ) mat [ 0 ] [ j ] = max ( val [ i ] + mat [ 1 ] [ j - wt [ i ] ] , mat [ 1 ] [ j ] ) ; else mat [ 0 ] [ j ] = mat [ 1 ] [ j ] ; } } i ++ ; }