并查集

  1. 亲戚题：已知a和b是亲戚，a和c是亲戚，则可以判断出b和c也是亲戚。
  2. 将多个集合合并成没有交集的集合。
 1 #include <iostream>
 2 using namespace std;
 3 
 4 int N, M, Q;
 5 int pre[20000], rak[20000];
 6 
 7 void MakeSet(int x)
 8 {
 9     pre[x] = -1;
10     rak[x] = 0;
11 }
12 
13 int FindSet(int x)
14 {
15     int r = x, q;
16     while (pre[r] != -1)
17         r = pre[r]; //此时r是代表节点
18     while (x != r)    //路径压缩
19     {
20         q = pre[x];
21         pre[x] = r; //将r作为所有非根节点的父节点
22         x = q;
23     }
24     return r;
25 }
26 
27 void UnionSet(int a, int b)
28 {
29     int t1 = FindSet(a);
30     int t2 = FindSet(b);
31     if (rak[t1] > rak[t2])
32         pre[t2] = t1;
33     else
34         pre[t1] = t2;
35     if (rak[t1] == rak[t2])
36         rak[t2]++;
37 }
38 
39 int main()
40 {
41     int i, a, b, m, n;
42     while (cin >> N >> M)
43     {
44         for (i = 1; i <= N; i++)
45             MakeSet(i);
46         for (i = 1; i <= M; i++)
47         {
48             cin >> a >> b;
49             if (FindSet(a) != FindSet(b))
50                 UnionSet(a, b);
51         }
52         cin >> Q;
53         for (i = 1; i <= Q; i++)
54         {
55             cin >> m >> n;
56             if (FindSet(m) != FindSet(n))
57                 cout << m << ' ' << n << " No" << endl;
58             else
59                 cout << m << ' ' << n << " Yes" << endl;
60         }
61     }
62 }

 

posted on 2013-06-20 11:02  月moon鸟  阅读(170)  评论(0)    收藏  举报

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