LeetCode 沙漏的最大总和

以最中间的的那个元素来移动，整个沙漏移动

class Solution {
    public int maxSum(int[][] grid) {
      int max = 0;
        int sum = 0;
        for (int i = 1; i < grid.length - 1; i++) {
            for (int j = 1; j < grid[0].length - 1; j++) {
                sum = grid[i][j] + grid[i - 1][j] + grid[i - 1][j - 1] + grid[i - 1][j + 1] +grid[i + 1][j] + grid[i + 1][j - 1] + grid[i + 1][j + 1];
                if (sum >= max) {
                    max = sum;
                    sum = 0;
                }
            }
        }
        return max;
    }
}