public class Solution {
public int[][] updateMatrix(int[][] matrix) {
int m = matrix.length;
int n = matrix[0].length;
Queue queue = new LinkedList<>();
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
if (matrix[i][j] == 0) {
queue.offer(new int[] {i, j});
}
else {
matrix[i][j] = Integer.MAX_VALUE;
}
}
}
int[][] dirs = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};
while (!queue.isEmpty()) {
int[] cell = queue.poll();
for (int[] d : dirs) {
int r = cell[0] + d[0];
int c = cell[1] + d[1];
if (r < 0 ||
r >= m ||
c < 0 ||
c >= n ||
matrix[r][c] <= matrix[cell[0]][cell[1]] + 1) {
continue;
}
queue.add(new int[] {r, c});
matrix[r][c] = matrix[cell[0]][cell[1]] + 1;
}
}
return matrix;
}
}