2373. Largest Local Values in a Matrix.py

'''
You are given an n x n integer matrix grid.

Generate an integer matrix maxLocal of size (n - 2) x (n - 2) such that:

maxLocal[i][j] is equal to the largest value of the 3 x 3 matrix in grid centered around row i + 1 and column j + 1.
In other words, we want to find the largest value in every contiguous 3 x 3 matrix in grid.

Return the generated matrix.

 

Example 1:


Input: grid = [[9,9,8,1],[5,6,2,6],[8,2,6,4],[6,2,2,2]]
Output: [[9,9],[8,6]]
Explanation: The diagram above shows the original matrix and the generated matrix.
Notice that each value in the generated matrix corresponds to the largest value of a contiguous 3 x 3 matrix in grid.
Example 2:


Input: grid = [[1,1,1,1,1],[1,1,1,1,1],[1,1,2,1,1],[1,1,1,1,1],[1,1,1,1,1]]
Output: [[2,2,2],[2,2,2],[2,2,2]]
Explanation: Notice that the 2 is contained within every contiguous 3 x 3 matrix in grid.
 

Constraints:

n == grid.length == grid[i].length
3 <= n <= 100
1 <= grid[i][j] <= 100
'''


class Solution:
    def largestLocal(self, grid: List[List[int]]) -> List[List[int]]:
        n, res = len(grid), []

        for i in range(1, n - 1):
            temp_row = []
            for j in range(1, n - 1):
                temp = 0

                for k in range(i - 1, i + 2):
                    for l in range(j - 1, j + 2):
                        temp = max(temp, grid[k][l])

                temp_row.append(temp)
            res.append(temp_row)

        return res