[poj2524]Ubiquitous Religions

题目←

裸的并查集，比较在意老师的扩展：如果包括两个同学不信仰一种宗教的关系，好像要用到hash？

#include<iostream>#include<cstdio>#include<algorithm>using namespace std;const int MAXN = 100000 + 50;int fa[MAXN],n,m,a,b;void init(int n){    for(int i = 1;i <= n;i ++)        fa[i] = i;}int find(int x){    return fa[x] == x ? x : fa[x] = find(fa[x]);}void merge(int a,int b){    a = find(a);    b = find(b);    fa[b] = a;}int cnt;int main(){    while(true)    {        cnt ++;        scanf("%d%d",&n,&m);        if(!n && !m)        {            return 0;        }        init(n);        for(int i = 1;i <= m;i ++)        {            scanf("%d%d",&a,&b);            merge(a,b);        }        int temp = n;        for(int i = 1;i <= n;i ++)        {            int t = find(i);            if(t != i)temp --;        }        printf("Case %d: %d\n",cnt,temp);    }    return 0;}