leetcode

2428.cpp (465B)

 class Solution {
   public:
     int maxSum(const vector<vector<int>> &grid) {
         int m = grid.size(), n = grid[0].size(), res = 0;
         for (int i = 0; i < m - 2; ++i) {
             for (int j = 0; j < n - 2; ++j)
                 res = max(res, grid[i + 0][j] + grid[i + 0][j + 1] + grid[i + 0][j + 2] + grid[i + 1][j + 1] +
                                    grid[i + 2][j] + grid[i + 2][j + 1] + grid[i + 2][j + 2]);
         }
         return res;
     }
 };