3567 - Minimum Absolute Difference in Sliding Submatrix.

Medium

You are given an m x n integer matrix grid and an integer k.

For every contiguous k x k submatrix of grid, compute the minimum absolute difference between any two distinct values within that submatrix.

Return a 2D array ans of size (m - k + 1) x (n - k + 1), where ans[i][j] is the minimum absolute difference in the submatrix whose top-left corner is (i, j) in grid.

Note: If all elements in the submatrix have the same value, the answer will be 0.

A submatrix (x1, y1, x2, y2) is a matrix that is formed by choosing all cells matrix[x][y] where x1 <= x <= x2 and y1 <= y <= y2.

Example 1:

Input: grid = [1,8,3,-2], k = 2

Output: [2]

Explanation:

• There is only one possible k x k submatrix: [[1, 8], [3, -2]].

• Distinct values in the submatrix are [1, 8, 3, -2].

• The minimum absolute difference in the submatrix is |1 - 3| = 2. Thus, the answer is [[2]].

Example 2:

Input: grid = [3,-1], k = 1

Output: [0,0]

Explanation:

• Both k x k submatrix has only one distinct element.

• Thus, the answer is [[0, 0]].

Example 3:

Input: grid = [1,-2,3,2,3,5], k = 2

Output: [1,2]

Explanation:

• There are two possible k × k submatrix:

• Thus, the answer is [[1, 2]].

Constraints:

• 1 <= m == grid.length <= 30

• 1 <= n == grid[i].length <= 30

• <code>-10⁵<= gridj<= 10⁵</code>

• 1 <= k <= min(m, n)