1219

class Solution {
public:
    int dfs(vector<vector<int>>& g, int i, int j) {
      if (i < 0 || j < 0 || i >= g.size() || j >= g[i].size() || g[i][j] <= 0)  return 0;
      g[i][j] = -g[i][j];
      auto res = max({ dfs(g, i + 1, j), dfs(g, i, j + 1), dfs(g, i - 1, j), dfs(g, i, j - 1) });
      g[i][j] = -g[i][j];
      return g[i][j] + res;
    }
    int getMaximumGold(vector<vector<int>>& grid, int res = 0) {
      for (auto i = 0; i < grid.size(); ++i)
        for (auto j = 0; j < grid[i].size(); ++j)
          res = max(res, dfs(grid, i, j));
      return res;
    }
};