一刷841

Author: diguage

README.adoc

@@ -5912,14 +5912,14 @@ TIP: **公众号的微信号是: `jikerizhi`**。__因为众所周知的原因
 //|{doc_base_url}/0840-magic-squares-in-grid.adoc[题解]
 //|Easy
 //|
-//
-//|{counter:codes}
-//|{leetcode_base_url}/keys-and-rooms/[841. Keys and Rooms^]
-//|{source_base_url}/_0841_KeysAndRooms.java[Java]
-//|{doc_base_url}/0841-keys-and-rooms.adoc[题解]
-//|Medium
-//|
-//
+
+|{counter:codes}
+|{leetcode_base_url}/keys-and-rooms/[841. Keys and Rooms^]
+|{source_base_url}/_0841_KeysAndRooms.java[Java]
+|{doc_base_url}/0841-keys-and-rooms.adoc[题解]
+|Medium
+|
+
 //|{counter:codes}
 //|{leetcode_base_url}/split-array-into-fibonacci-sequence/[842. Split Array into Fibonacci Sequence^]
 //|{source_base_url}/_0842_SplitArrayIntoFibonacciSequence.java[Java]

docs/0841-keys-and-rooms.adoc

@@ -1,56 +1,78 @@
 [#0841-keys-and-rooms]
-= 841. Keys and Rooms
+= 841. 钥匙和房间
 
-{leetcode}/problems/keys-and-rooms/[LeetCode - Keys and Rooms^]
+https://leetcode.cn/problems/keys-and-rooms/[LeetCode - 841. 钥匙和房间 ^]
 
-There are `N` rooms and you start in room `0`.  Each room has a distinct number in `0, 1, 2, ..., N-1`, and each room may have some keys to access the next room. 
+有 `n` 个房间，房间按从 `0` 到 `n - 1` 编号。最初，除 `0` 号房间外的其余所有房间都被锁住。你的目标是进入所有的房间。然而，你不能在没有获得钥匙的时候进入锁住的房间。
 
-Formally, each room `i` has a list of keys `rooms[i]`, and each key `rooms[i][j]` is an integer in `[0, 1, ..., N-1]` where `N = rooms.length`.  A key `rooms[i][j] = v` opens the room with number `v`.
+当你进入一个房间，你可能会在里面找到一套 *不同的钥匙*，每把钥匙上都有对应的房间号，即表示钥匙可以打开的房间。你可以拿上所有钥匙去解锁其他房间。
 
-Initially, all the rooms start locked (except for room `0`). 
+给你一个数组 `rooms` 其中 `rooms[i]` 是你进入 `i` 号房间可以获得的钥匙集合。如果能进入 *所有* 房间返回 `true`，否则返回 `false`。
 
-You can walk back and forth between rooms freely.
 
-Return `true` if and only if you can enter every room.
+*示例 1：*
 
+....
+输入：rooms = [[1],[2],[3],[]]
+输出：true
+解释：
+我们从 0 号房间开始，拿到钥匙 1。
+之后我们去 1 号房间，拿到钥匙 2。
+然后我们去 2 号房间，拿到钥匙 3。
+最后我们去了 3 号房间。
+由于我们能够进入每个房间，我们返回 true。
+....
 
+*示例 2：*
 
+....
+输入：rooms = [[1,3],[3,0,1],[2],[0]]
+输出：false
+解释：我们不能进入 2 号房间。
+....
 
-*Example 1:*
 
-[subs="verbatim,quotes,macros"]
-----
-*Input:* [[1],[2],[3],[]]
-*Output:* true
-*Explanation:  *
-We start in room 0, and pick up key 1.
-We then go to room 1, and pick up key 2.
-We then go to room 2, and pick up key 3.
-We then go to room 3.  Since we were able to go to every room, we return true.
-----
-
-*Example 2:*
-
-[subs="verbatim,quotes,macros"]
-----
-*Input:* [[1,3],[3,0,1],[2],[0]]
-*Output:* false
-*Explanation:* We can't enter the room with number 2.
-----
+*提示：*
 
-*Note:*
+* `n == rooms.length`
+* `+2 <= n <= 1000+`
+* `+0 <= rooms[i].length <= 1000+`
+* `+1 <= sum(rooms[i].length) <= 3000+`
+* `+0 <= rooms[i][j] < n+`
+* 所有 `rooms[i]` 的值 *互不相同*
 
 
-. `1 <= rooms.length <= 1000`
-. `0 <= rooms[i].length <= 1000`
-. The number of keys in all rooms combined is at most `3000`.
-
+== 思路分析
 
+根据钥匙，把房间走一遍即可。可以使用备忘录来防止重复走同一个房间来加快速度。
 
+既可以深度优先遍历，也可以广度优先遍历。如果使用深度优先遍历，需要使用递归。
 
 [[src-0841]]
+[tabs]
+====
+一刷::
++
+--
 [{java_src_attr}]
 ----
 include::{sourcedir}/_0841_KeysAndRooms.java[tag=answer]
 ----
+--
+
+// 二刷::
+// +
+// --
+// [{java_src_attr}]
+// ----
+// include::{sourcedir}/_0841_KeysAndRooms_2.java[tag=answer]
+// ----
+// --
+====
+
+
+== 参考资料
+
+. https://leetcode.cn/problems/keys-and-rooms/solutions/393524/yao-chi-he-fang-jian-by-leetcode-solution/[841. 钥匙和房间 - 官方题解^]
+. https://leetcode.cn/problems/keys-and-rooms/solutions/18826/7xing-dfs-8xing-bfs-liang-chong-fang-fa-san-chong-/[841. 钥匙和房间 - 7行DFS 8行BFS 两种方法 三种实现 超详细^]
 

docs/index.adoc

@@ -1765,7 +1765,7 @@ include::0796-rotate-string.adoc[leveloffset=+1]
 
 // include::0840-magic-squares-in-grid.adoc[leveloffset=+1]
 
-// include::0841-keys-and-rooms.adoc[leveloffset=+1]
+include::0841-keys-and-rooms.adoc[leveloffset=+1]
 
 // include::0842-split-array-into-fibonacci-sequence.adoc[leveloffset=+1]
 

logbook/202503.adoc

@@ -803,6 +803,12 @@ endif::[]
 |{doc_base_url}/1006-clumsy-factorial.adoc[题解]
 |✅ 栈。代码写出来了，但是好烂！
 
+|{counter:codes2503}
+|{leetcode_base_url}/keys-and-rooms/[841. 钥匙和房间^]
+|{doc_base_url}/0841-keys-and-rooms.adoc[题解]
+|✅ 深度优先遍历或广度优先遍历。
+
+
 |===
 
 截止目前，本轮练习一共完成 {codes2503} 道题。

src/main/java/com/diguage/algo/leetcode/_0841_KeysAndRooms.java

@@ -0,0 +1,33 @@
+package com.diguage.algo.leetcode;
+
+import java.util.*;
+
+public class _0841_KeysAndRooms {
+  // tag::answer[]
+  /**
+   * @author D瓜哥 · https://www.diguage.com
+   * @since 2025-05-24 18:48:35
+   */
+  public boolean canVisitAllRooms(List<List<Integer>> rooms) {
+    Queue<Integer> queue = new LinkedList<>();
+    queue.addAll(rooms.get(0));
+    rooms.set(0, null);
+    while (!queue.isEmpty()) {
+      Integer key = queue.poll();
+      List<Integer> keys = rooms.get(key);
+      if (keys != null) {
+        queue.addAll(keys);
+        rooms.set(key, null);
+      }
+    }
+    return rooms.stream().allMatch(Objects::isNull);
+  }
+  // end::answer[]
+
+  public static void main(String[] args) {
+    ;
+    new _0841_KeysAndRooms().canVisitAllRooms(
+      new ArrayList<List<Integer>>(List.of(List.of(1, 3), List.of(3, 0, 1), List.of(2), List.of(0)))
+    );
+  }
+}