class Solution {
private static final int[][] DIRS = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};
public int[][] updateMatrix(int[][] mat) {
int numRows = mat.length;
int numCols = mat[0].length;
int[][] distances = new int[numRows][numCols];
Queue queue = new LinkedList<>();
for (int i = 0; i < numRows; i++) {
for (int j = 0; j < numCols; j++) {
if (mat[i][j] == 0) {
queue.add(new int[]{i, j});
} else {
distances[i][j] = Integer.MAX_VALUE;
}
}
}
while (!queue.isEmpty()) {
int[] removed = queue.remove();
int currX = removed[0];
int currY = removed[1];
for (int[] dir : DIRS) {
int newX = currX + dir[0];
int newY = currY + dir[1];
if (newX >= 0 && newY >= 0 && newX < numRows && newY < numCols && distances[newX][newY] > distances[currX][currY] + 1) {
queue.add(new int[]{newX, newY});
distances[newX][newY] = distances[currX][currY] + 1;
}
}
}
return distances;
}
}