POJ 2524 Ubiquitous Religions

 1 //直接并查集
 2 #include<cstdio>
 3 #include<cstdlib>
 4 #include<cstring>
 5 #include<algorithm>
 6 #include<iostream>
 7 using namespace std;
 8 int n,m;
 9 int fa[505000];
10 int find(int x){
11     return fa[x]==x?fa[x]:fa[x]=find(fa[x]);
12 }
13 int join(int x,int y){
14     int fx=find(x),
15         fy=find(y);
16     if(fx!=fy)fa[fx]=fy;
17 }
18 int main()
19 {
20     int n,m,cnt=1;
21     while(scanf("%d%d",&n,&m)==2&&n&&m){
22         for(int i=1;i<=n;i++) fa[i]=i;
23         while(m--){
24             int a,b;
25             scanf("%d%d",&a,&b);
26             join(a,b);
27         }
28         int sum=0;
29         for(int i=1;i<=n;i++)
30           if(fa[i]==i) sum++;
31         printf("Case %d: %d\n",cnt,sum);
32         cnt++;
33     }
34     return 0;
35 }