79. (2428) Maximum Sum of an Hourglass - Leetcode.cpp

/*
You are given an m x n integer matrix grid.

We define an hourglass as a part of the matrix with the following form:

Return the maximum sum of the elements of an hourglass.

Note that an hourglass cannot be rotated and must be entirely contained within the matrix.
*/

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