3643 - Flip Square Submatrix Vertically.

Easy

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:

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)