0840. Magic Squares In Grid

https://leetcode.com/problems/magic-squares-in-grid

Description

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 a row x col grid of integers, how many 3 x 3 "magic square" subgrids are there? (Each subgrid is contiguous).

Example 1:

**Input:** grid = [[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:
![](https://assets.leetcode.com/uploads/2020/09/11/magic_valid.jpg)
while this one is not:
![](https://assets.leetcode.com/uploads/2020/09/11/magic_invalid.jpg)
In total, there is only one magic square inside the given grid.

Example 2:

**Input:** grid = [[8]]
**Output:** 0

Example 3:

**Input:** grid = [[4,4],[3,3]]
**Output:** 0

Example 4:

**Input:** grid = [[4,7,8],[9,5,1],[2,3,6]]
**Output:** 0

Constraints:

• row == grid.length

• col == grid[i].length

• 1 <= row, col <= 10

• 0 <= grid[i][j] <= 15

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