For each element , check both elements just below the number and below left to the number add the maximum of them to it
if ( j - 1 >= 0 ) tri [ i ] [ j ] += Math . max ( tri [ i + 1 ] [ j ] , tri [ i + 1 ] [ j - 1 ] ) ; else tri [ i ] [ j ] += tri [ i + 1 ] [ j ] ; ans = Math . max ( ans , tri [ i ] [ j ] ) ; } }