114 lines
3.0 KiB
Java
114 lines
3.0 KiB
Java
//你被给定一个 m × n 的二维网格 rooms ，网格中有以下三种可能的初始化值：
|
||
//
|
||
//
|
||
// -1 表示墙或是障碍物
|
||
// 0 表示一扇门
|
||
// INF 无限表示一个空的房间。然后，我们用 231 - 1 = 2147483647 代表 INF。你可以认为通往门的距离总是小于 2147483647
|
||
//的。
|
||
//
|
||
//
|
||
// 你要给每个空房间位上填上该房间到 最近门的距离 ，如果无法到达门，则填 INF 即可。
|
||
//
|
||
//
|
||
//
|
||
// 示例 1：
|
||
//
|
||
//
|
||
//输入：rooms = [[2147483647,-1,0,2147483647],[2147483647,2147483647,2147483647,-1]
|
||
//,[2147483647,-1,2147483647,-1],[0,-1,2147483647,2147483647]]
|
||
//输出：[[3,-1,0,1],[2,2,1,-1],[1,-1,2,-1],[0,-1,3,4]]
|
||
//
|
||
//
|
||
// 示例 2：
|
||
//
|
||
//
|
||
//输入：rooms = [[-1]]
|
||
//输出：[[-1]]
|
||
//
|
||
//
|
||
// 示例 3：
|
||
//
|
||
//
|
||
//输入：rooms = [[2147483647]]
|
||
//输出：[[2147483647]]
|
||
//
|
||
//
|
||
// 示例 4：
|
||
//
|
||
//
|
||
//输入：rooms = [[0]]
|
||
//输出：[[0]]
|
||
//
|
||
//
|
||
//
|
||
//
|
||
// 提示：
|
||
//
|
||
//
|
||
// m == rooms.length
|
||
// n == rooms[i].length
|
||
// 1 <= m, n <= 250
|
||
// rooms[i][j] 是 -1、0 或 231 - 1
|
||
//
|
||
// Related Topics 广度优先搜索 数组 矩阵
|
||
// 👍 154 👎 0
|
||
|
||
package leetcode.editor.cn;
|
||
|
||
import java.util.Arrays;
|
||
import java.util.LinkedList;
|
||
import java.util.List;
|
||
import java.util.Queue;
|
||
|
||
//286:墙与门
|
||
public class WallsAndGates {
|
||
public static void main(String[] args) {
|
||
//测试代码
|
||
Solution solution = new WallsAndGates().new Solution();
|
||
}
|
||
|
||
//力扣代码
|
||
//leetcode submit region begin(Prohibit modification and deletion)
|
||
class Solution {
|
||
private static final int EMPTY = Integer.MAX_VALUE;
|
||
private static final int GATE = 0;
|
||
private final List<int[]> DIRECTIONS = Arrays.asList(
|
||
new int[]{1, 0},
|
||
new int[]{-1, 0},
|
||
new int[]{0, 1},
|
||
new int[]{0, -1}
|
||
);
|
||
|
||
public void wallsAndGates(int[][] rooms) {
|
||
int m = rooms.length;
|
||
if (m == 0) {
|
||
return;
|
||
}
|
||
int n = rooms[0].length;
|
||
Queue<int[]> q = new LinkedList<>();
|
||
for (int row = 0; row < m; row++) {
|
||
for (int col = 0; col < n; col++) {
|
||
if (rooms[row][col] == GATE) {
|
||
q.add(new int[]{row, col});
|
||
}
|
||
}
|
||
}
|
||
while (!q.isEmpty()) {
|
||
int[] point = q.poll();
|
||
int row = point[0];
|
||
int col = point[1];
|
||
for (int[] direction : DIRECTIONS) {
|
||
int r = row + direction[0];
|
||
int c = col + direction[1];
|
||
if (r < 0 || c < 0 || r >= m || c >= n || rooms[r][c] != EMPTY) {
|
||
continue;
|
||
}
|
||
rooms[r][c] = rooms[row][col] + 1;
|
||
q.add(new int[]{r, c});
|
||
}
|
||
}
|
||
}
|
||
}
|
||
//leetcode submit region end(Prohibit modification and deletion)
|
||
|
||
} |