01-matrix

Given an m x n binary matrix mat, return the distance of the nearest 0 for each cell.

The distance between two adjacent cells is 1.

Example 1:

Input: mat = [[0,0,0],[0,1,0],[0,0,0]]
Output: [[0,0,0],[0,1,0],[0,0,0]]

Example 2:

Input: mat = [[0,0,0],[0,1,0],[1,1,1]]
Output: [[0,0,0],[0,1,0],[1,2,1]]

Constraints:

• m == mat.length


• n == mat[i].length


• 1 <= m, n <= 104


• 1 <= m * n <= 104


• mat[i][j] is either 0 or 1.


• There is at least one 0 in mat.