[Swift]LeetCode851. 喧鬧和富有 | Loud and Rich

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➤微信公衆號：山青詠芝（shanqingyongzhi）
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In a group of N people (labelled 0, 1, 2, ..., N-1), each person has different amounts of money, and different levels of quietness.

For convenience, we'll call the person with label x, simply "person x".

We'll say that richer[i] = [x, y] if person x definitely has more money than person y.  Note that richer may only be a subset of valid observations.

Also, we'll say quiet[x] = q if person x has quietness q.

Now, return answer, where answer[x] = y if y is the least quiet person (that is, the person y with the smallest value of quiet[y]), among all people who definitely have equal to or more money than person x.

Example 1:

Input: richer = [[1,0],[2,1],[3,1],[3,7],[4,3],[5,3],[6,3]], quiet = [3,2,5,4,6,1,7,0] Output: [5,5,2,5,4,5,6,7] Explanation: answer[0] = 5. Person 5 has more money than 3, which has more money than 1, which has more money than 0. The only person who is quieter (has lower quiet[x]) is person 7, but it isn't clear if they have more money than person 0. answer[7] = 7. Among all people that definitely have equal to or more money than person 7 (which could be persons 3, 4, 5, 6, or 7), the person who is the quietest (has lower quiet[x]) is person 7. The other answers can be filled out with similar reasoning. 

Note:

1. 1 <= quiet.length = N <= 500
2. 0 <= quiet[i] < N, all quiet[i] are different.
3. 0 <= richer.length <= N * (N-1) / 2
4. 0 <= richer[i][j] < N
5. richer[i][0] != richer[i][1]
6. richer[i]'s are all different.
7. The observations in richer are all logically consistent.

---

在一組 N 我的（編號爲 0, 1, 2, ..., N-1）中，每一個人都有不一樣數目的錢，以及不一樣程度的安靜（quietness）。

爲了方便起見，咱們將編號爲 x 的人簡稱爲 "person x "。

若是可以確定 person x 比 person y 更有錢的話，咱們會說 richer[i] = [x, y] 。注意 richer 可能只是有效觀察的一個子集。

另外，若是 person x 的安靜程度爲 q ，咱們會說 quiet[x] = q 。

如今，返回答案 answer ，其中 answer[x] = y 的前提是，在全部擁有的錢很多於 person x 的人中，person y 是最安靜的人（也就是安靜值 quiet[y] 最小的人）。

示例：

輸入：richer = [[1,0],[2,1],[3,1],[3,7],[4,3],[5,3],[6,3]], quiet = [3,2,5,4,6,1,7,0]
輸出：[5,5,2,5,4,5,6,7]
解釋： 
answer[0] = 5，
person 5 比 person 3 有更多的錢，person 3 比 person 1 有更多的錢，person 1 比 person 0 有更多的錢。
惟一較爲安靜（有較低的安靜值 quiet[x]）的人是 person 7，
可是目前還不清楚他是否比 person 0 更有錢。

answer[7] = 7，
在全部擁有的錢確定很多於 person 7 的人中(這可能包括 person 3，4，5，6 以及 7)，
最安靜(有較低安靜值 quiet[x])的人是 person 7。

其餘的答案也能夠用相似的推理來解釋。

提示：

1. 1 <= quiet.length = N <= 500
2. 0 <= quiet[i] < N，全部 quiet[i] 都不相同。
3. 0 <= richer.length <= N * (N-1) / 2
4. 0 <= richer[i][j] < N
5. richer[i][0] != richer[i][1]
6. richer[i] 都是不一樣的。
7. 對 richer 的觀察在邏輯上是一致的。 

---

Runtime: 488 ms

Memory Usage: 21.4 MB

 1 class Solution {
 2     var richer2:[Int:[Int]] = [Int:[Int]]()
 3     var res:[Int] = [Int]()
 4     func loudAndRich(_ richer: [[Int]], _ quiet: [Int]) -> [Int] {
 5         var n:Int = quiet.count
 6         for i in 0..<n
 7         {
 8             richer2[i] = [Int]()            
 9         }
10         for v in richer
11         {
12             richer2[v[1],default:[Int]()].append(v[0])            
13         }
14         res = [Int](repeating:-1,count:n)
15         for i in 0..<n
16         {
17             dfs(i, quiet)
18         }
19         return res
20     }
21     
22     func dfs(_ i:Int,_ quiet:[Int]) -> Int
23     {
24         if res[i] >= 0 {return res[i]}
25         res[i] = i
26         for j in richer2[i,default:[Int]()]
27         {
28             if quiet[res[i]] > quiet[dfs(j, quiet)]
29             {
30                 res[i] = res[j]
31             }
32         }
33         return res[i]
34     }
35 }

---

Runtime: 540 ms

Memory Usage: 22.2 MB

 1 class Solution {
 2     func loudAndRich(_ richer: [[Int]], _ quiet: [Int]) -> [Int] {       
 3         //這是個列表，
 4         var mans:[Man] = (0 ..< quiet.count).map{Man.init(index: $0, quiet: quiet[$0],quiets: quiet)}
 5         //作成單向鏈表 叫這個名字吧？
 6         for paired in richer {            mans[paired.last!].richs.insert(mans[paired.first!])
 7         }        
 8         //存 結果答案
 9         var result:[Int] = []
10         //遍歷答案
11         for e in mans {            
12             result.append(
13                 e.mostQuietMan.index
14             )            
15         }
16         return result        
17     }
18 }
19 
20 /// 抽象的人
21 class Man {
22     var index:Int //本身的位置
23     var quiet:Int //安靜度    
24     var quiets:[Int]
25     var richs:Set<Man> = [] //比本身富的人，用set可去重，有層數
26     init(index:Int,quiet:Int, quiets: [Int]){
27         self.index = index
28         self.quiet = quiet
29         self.quiets = quiets
30     }
31     lazy var mostQuietMan = getmostQuietMan(quiet: self.quiets)
32     func getmostQuietMan(quiet: [Int]) -> Man {
33         var mostQuietMan = self
34         for man in self.richs{
35             if quiet[man.index] < quiet[mostQuietMan.index]{
36                 mostQuietMan = man
37             }
38             if quiet[man.mostQuietMan.index] < quiet[mostQuietMan.index] {
39                 mostQuietMan = man.mostQuietMan
40             }
41         }
42         return mostQuietMan
43     }    
44 }
45 
46 //Set須要遵循hashable
47 extension Man:Hashable {
48     static func == (lhs: Man, rhs: Man) -> Bool {
49         return lhs.index == rhs.index
50     }
51     
52     var hashValue:Int {
53         return self.index
54     }
55 }

---

Runtime: 3172 ms

Memory Usage: 34.3 MB

 1 class Solution {
 2     func loudAndRich(_ richer: [[Int]], _ quiet: [Int]) -> [Int] {
 3         var mans:[Man] = (0 ..< quiet.count).map{  Man.init(index: $0, quiet: quiet[$0])}
 4         //作成單向鏈表 叫這個名字吧？
 5         for paired in richer {
 6             mans[paired.last!].richs.insert(mans[paired.first!])
 7         }
 8         var result:[Int] = []
 9         
10         for e in mans {            
11             result.append(
12             e.richers.min { (a, b) -> Bool in
13                return a.quiet < b.quiet
14             }!.index
15             )            
16         }               
17         return result        
18     }
19 }
20 
21 class Man {
22     var index:Int
23     var quiet:Int
24     var richs:Set<Man> = []
25     init(index:Int,quiet:Int){
26         self.index = index
27         self.quiet = quiet
28     }
29     lazy var richers:Set<Man> = self.getRichers()
30     func getRichers() -> Set<Man> {        
31             var rs:Set<Man> = richs
32             for e in richs {
33                 rs = rs.union(e.richers)
34             }
35             rs.insert(self)
36             return rs        
37     }    
38 }
39 
40 extension Man:Hashable {
41     static func == (lhs: Man, rhs: Man) -> Bool {
42         return lhs.index == rhs.index
43     }
44     
45     var hashValue:Int {
46         return self.index
47     }
48 }