並查集 POj 2524

題目點這裏

題目大意

和上一篇HDU1213一樣，最基本的並查集題目

代碼

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
const int M = 50005;
int id[M];
int count;
int find(int p)
{
    while(p != id[p])   p = id[p];
    return p;
}
bool connected(int p,int q)
{
    return find(p) == find(q);
}
void unionn(int p,int q)
{
    int pRoot = find(p);
    int qRoot = find(q);
    if(pRoot == qRoot)  return;

    id[pRoot] = qRoot;

    --count;
}
int main()
{
    int n,m;
    int ans = 0;
    while(scanf("%d%d",&n,&m))
    {
        if(n == 0 && m == 0)
            break;
        count = n;
        for(int i = 1;i <= n; i++)
            id[i] = i;      
        while(m--)
        {
            int p,q;
            scanf("%d%d",&p,&q); 
            unionn(p,q);
        }
        printf("Case %d: %d\n",++ans,count);
    }       
    return 0;
 }