Given an m x n binary matrix mat, return the distance of the nearest 0 for each cell.
The distance between two cells sharing a common edge is 1.
m == mat.lengthn == mat[i].length1 <= m, n <= 10^41 <= m * n <= 10^4mat[i][j] is either 0 or 10 in matmat = [[0,0,0],[0,1,0],[0,0,0]][[0,0,0],[0,1,0],[0,0,0]]mat = [[0,0,0],[0,1,0],[1,1,1]][[0,0,0],[0,1,0],[1,2,1]]