#840
Magic Squares In Grid
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array · hash table · math · matrix
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?
Note: while a magic square can only contain numbers from 1 to 9, grid may contain numbers up to 15.
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:
Example 2:
while this one is not:
Example 3:
In total, there is only one magic square inside the given grid.
Example 4:
Input: grid = [[8]]
Output: 0
Solution