poj1611 并查集

题目链接：http://poj.org/problem?id=1611

#include <cstdio>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <cstring>
#include <queue>
#include <vector>

#define maxn 30050
#define INF  0x3f3f3f
using namespace std;
int pa[maxn];  
    
int find(int x){
    return x == pa[x] ? x : pa[x] = find(pa[x]);
}
int main()
{
    int n,m;
    while(scanf("%d%d",&n,&m)){
        if(!n && !m)   break;
        for(int i=0;i<n;i++) pa[i] = i;
        
        for(int i=1;i<=m;i++){
               int k;
               scanf("%d",&k);
               if(!k) continue;
               int a,b;
               scanf("%d",&a);
               k--;
               while(k--){
                  scanf("%d",&b);
                  int ta = find(a);
                  int tb = find(b);
                  if(ta != tb){
                        if(ta < tb) pa[tb] = ta;
                        else        pa[ta] = tb;
                  }
               }
        }
        int ans = 1;
        for(int i=1;i<n;i++){
            if(find(i) == 0) ans++;
        }
        printf("%d
",ans);
    }
}