Construct rest of the tSum array
for ( i = 1 ; i < l ; i ++ ) for ( j = 1 ; j < m ; j ++ ) for ( k = 1 ; k < n ; k ++ ) tSum [ i ] [ j ] [ k ] = min ( tSum [ i - 1 ] [ j ] [ k ] , tSum [ i ] [ j - 1 ] [ k ] , tSum [ i ] [ j ] [ k - 1 ] ) + arr [ i ] [ j ] [ k ] ; return tSum [ l - 1 ] [ m - 1 ] [ n - 1 ] ; }