Initialize first row - First column of tSum array
for ( i = 1 ; i < l ; i ++ ) for ( j = 1 ; j < m ; j ++ ) tSum [ i ] [ j ] [ 0 ] = min ( tSum [ i - 1 ] [ j ] [ 0 ] , tSum [ i ] [ j - 1 ] [ 0 ] , INT_MAX ) + arr [ i ] [ j ] [ 0 ] ;