[Swift]LeetCode841. 鑰匙和房間 | Keys and Rooms

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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. 

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.

Initially, all the rooms start locked (except for room 0). 

You can walk back and forth between rooms freely.

Return true if and only if you can enter every room.

Example 1:

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:

Input: [[1,3],[3,0,1],[2],[0]]
Output: false
Explanation: We can't enter the room with number 2.

Note:

1. 1 <= rooms.length <= 1000
2. 0 <= rooms[i].length <= 1000
3. The number of keys in all rooms combined is at most 3000.

---

有 N 個房間，開始時你位於 0 號房間。每一個房間有不一樣的號碼：0，1，2，...，N-1，而且房間裏可能有一些鑰匙能使你進入下一個房間。

在形式上，對於每一個房間 i 都有一個鑰匙列表 rooms[i]，每一個鑰匙 rooms[i][j] 由 [0,1，...，N-1] 中的一個整數表示，其中 N = rooms.length。 鑰匙 rooms[i][j] = v 能夠打開編號爲 v 的房間。

最初，除 0 號房間外的其他全部房間都被鎖住。

你能夠自由地在房間之間來回走動。

若是能進入每一個房間返回 true，不然返回 false。

示例 1：

輸入: [[1],[2],[3],[]]
輸出: true
解釋:  
咱們從 0 號房間開始，拿到鑰匙 1。
以後咱們去 1 號房間，拿到鑰匙 2。
而後咱們去 2 號房間，拿到鑰匙 3。
最後咱們去了 3 號房間。
因爲咱們可以進入每一個房間，咱們返回 true。

示例 2：

輸入：[[1,3],[3,0,1],[2],[0]]
輸出：false
解釋：咱們不能進入 2 號房間。

提示：

1. 1 <= rooms.length <= 1000
2. 0 <= rooms[i].length <= 1000
3. 全部房間中的鑰匙數量總計不超過 3000。

---

40ms

 1 class Solution {
 2     func canVisitAllRooms(_ rooms: [[Int]]) -> Bool {
 3         var keys: [Int] = Array(repeating: -1, count: rooms.count)
 4         var result:[Int] = [0]
 5         keys[0] = 0
 6         var i: Int = 0
 7         while i < result.count {
 8             for each in rooms[result[i]] {
 9                 if keys[each] == -1 {
10                     result.append(each)
11                     keys[each] = 0
12                 }
13             }
14             if result.count == rooms.count {
15                 return true
16             }
17             i += 1
18         }
19         return false
20     }
21 }

---

Runtime: 44 ms

Memory Usage: 19.4 MB

 1 class Solution {
 2     func canVisitAllRooms(_ rooms: [[Int]]) -> Bool {
 3         var dfs:[Int] = [Int]()
 4         dfs.append(0)
 5         var seen:Set<Int> = Set<Int>()
 6         seen.insert(0)
 7         while(!dfs.isEmpty)
 8         {
 9             var i:Int = dfs.removeLast()
10             for j in rooms[i]
11             {
12                 if !seen.contains(j)
13                 {
14                     dfs.append(j)
15                     seen.insert(j)
16                     if rooms.count == seen.count {return true}
17                 }
18             }
19         }
20         return rooms.count == seen.count
21     }
22 }

---

44ms

 1 class Solution {
 2     func canVisitAllRooms(_ rooms: [[Int]]) -> Bool {
 3         let count = rooms.count
 4         var seen = [Bool](repeating: false, count: count)
 5         seen[0] = true
 6         
 7         var keysInRoom = [Int]()
 8         keysInRoom.append(0)
 9         
10         while keysInRoom.count != 0 {
11             let room = keysInRoom.last!
12             keysInRoom.removeLast()
13             
14             let keys = rooms[room]
15             for key in keys {
16                 if !seen[key] {
17                     seen[key] = true
18                     keysInRoom.append(key)
19                 }
20             }
21         }
22         for s in seen {
23             if !s {
24                 return false
25             }
26         }
27         return true
28     }
29 }

---

48ms

 1 class Solution {
 2     func canVisitAllRooms(_ rooms: [[Int]]) -> Bool {
 3 
 4         var numberOfRooms = rooms.count
 5         var visited: [Int: Int] = [:]
 6         var stack: [Int] = []
 7         stack.append(0)
 8         visited[0] = 1
 9         
10         while(!stack.isEmpty) {
11             
12             var room = stack.removeLast()
13             var keys = rooms[room]
14             
15             for key in keys {
16                 if(visited[key] == nil) {
17                     visited[key] = 1
18                     stack.append(key)
19                 }
20             }            
21         }
22         return numberOfRooms == visited.keys.count
23     }
24 }

---

52ms

 1 class Solution {
 2     func canVisitAllRooms(_ rooms: [[Int]]) -> Bool {
 3         var key = Set(rooms[0])
 4         var open = [0:0]
 5         var nextOpen : Int? = 0
 6         while nextOpen != nil {
 7             nextOpen = nil
 8             for data in key {
 9                 if open[data] == nil {
10                 nextOpen = data
11                open[ data] = data
12                 for k in rooms[data]{
13                     key.insert(k)
14                  }
15                 key.remove(data)
16                 }
17             }
18         }
19         return open.count == rooms.count
20     }
21 }

---

64ms

 1 class Solution {
 2     func canVisitAllRooms(_ rooms: [[Int]]) -> Bool {
 3         var unvisited : Set<Int> = []
 4         var canVisit : [Int] = []
 5         
 6         for i in 0 ..< rooms.count {
 7             unvisited.insert(i)
 8         }
 9         
10         canVisit = rooms[0]
11         unvisited.remove(0)
12         
13         while !canVisit.isEmpty {
14             let room = canVisit.removeFirst()
15             if unvisited.contains(room) {
16                 canVisit.append(contentsOf: rooms[room])
17                 unvisited.remove(room)
18             }
19         }
20         
21         if unvisited.isEmpty {
22             return true
23         }
24         
25         return false
26     }
27 }

---

76ms

 1 class Solution {
 2     func canVisitAllRooms(_ rooms: [[Int]]) -> Bool {
 3         if (rooms.count <= 1) { return true }
 4         
 5         var visitedRooms: [Bool] = Array.init(repeating: false, count: rooms.count)
 6         visitedRooms[0] = true
 7         var queue: [Int] = []
 8         addKeysToQueue(&queue, 0, &visitedRooms, rooms)
 9         
10         while (!queue.isEmpty) {
11             addKeysToQueue(&queue, queue.removeLast(), &visitedRooms, rooms)
12         }
13         
14         for i in 0..<visitedRooms.count {
15             if (!visitedRooms[i]) {
16                 return false
17             }
18         }
19         return true
20     }
21     
22     func addKeysToQueue(_ queue: inout [Int], _ key: Int, _ visitedRooms: inout [Bool], _ rooms: [[Int]]) {
23         for i in 0..<rooms[key].count {
24             var nextRoom = rooms[key][i]
25             if (!visitedRooms[nextRoom]) {
26                 queue.append(nextRoom)
27                 visitedRooms[nextRoom] = true
28             }
29         }
30     }
31 }