POJ 2524 Ubiquitous Religions （带权并查集）

题目链接：Ubiquitous Religions

带权并查集，记录集合个数即可

代码：

#include <stdio.h>#include <string.h>const int N = 50005;int n, m, parent[N];int find(int x) {    if (x == parent[x])return x;    return parent[x] = find(parent[x]);}int main() {    int cas = 0;    while (~scanf("%d%d", &n, &m) && n + m) {for (int i = 1; i <= n; i++)    parent[i] = i;int a, b, ans = n;while (m--) {    scanf("%d%d", &a, &b);    int pa = find(a);    int pb = find(b);    if (pa != pb) {parent[pa] = pb;ans--;    }}printf("Case %d: %d\n", ++cas, ans);    }    return 0;}