Find the largest sum by considering all possible next elements in sequence .
int zzs = 0 ; for ( int k = 0 ; k < n ; k ++ ) if ( k != j ) zzs = max ( zzs , largestZigZagSumRec ( mat , i + 1 , k , n ) ) ; return ( dp [ i ] [ j ] = ( zzs + mat [ i ] [ j ] ) ) ; }