A 3 x 3 magic square is a 3 x 3 grid filled with distinct numbers from 1 to 9 such that each row, column, and both diagonals all have the same sum.
Given an grid of integers, how many 3 x 3 "magic square" subgrids are there? (Each subgrid is contiguous).
Example 1:
Input: [[4,3,8,4],
[9,5,1,9],
[2,7,6,2]]
Output: 1
Explanation:
The following subgrid is a 3 x 3 magic square:
438
951
276
while this one is not:
384
519
762
In total, there is only one magic square inside the given grid.
Note:
1 <= grid.length <= 101 <= grid[0].length <= 100 <= grid[i][j] <= 15s
参考资料：
https://leetcode.com/problems/magic-squares-in-grid/
[LeetCode] Magic Squares In Grid 网格中的神奇正方形
原文：https://www.cnblogs.com/grandyang/p/10404157.html