3973 Flip Square Submatrix Vertically

Flip Square Submatrix Vertically

You are given an m x n integer matrix grid, and three integers x, y, and k.

The integers x and y represent the row and column indices of the top-left corner of a square submatrix and the integer k represents the size (side length) of the square submatrix.

Your task is to flip the submatrix by reversing the order of its rows vertically.

Return the updated matrix.

 

Example 1:

Input: grid = [[1,2,3,4],[5,6,7,8],[9,10,11,12],[13,14,15,16]], x = 1, y = 0, k = 3

Output: [[1,2,3,4],[13,14,15,8],[9,10,11,12],[5,6,7,16]]

Explanation:

The diagram above shows the grid before and after the transformation.

Example 2:

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Input: grid = [[3,4,2,3],[2,3,4,2]], x = 0, y = 2, k = 2

Output: [[3,4,4,2],[2,3,2,3]]

Explanation:

The diagram above shows the grid before and after the transformation.

 

Constraints:

m == grid.length
n == grid[i].length
1 <= m, n <= 50
1 <= grid[i][j] <= 100
0 <= x < m
0 <= y < n
1 <= k <= min(m - x, n - y)

class Solution:
    def reverseSubmatrix(
        self, grid: List[List[int]], x: int, y: int, k: int
    ) -> List[List[int]]:
        i0, i1 = x, x + k - 1
        while i0 < i1:
            for j in range(y, y + k):
                grid[i0][j], grid[i1][j] = grid[i1][j], grid[i0][j]
            i0, i1 = i0 + 1, i1 - 1
        return grid