poj 1661(并查集)

#include<cstdio>
#include<iostream>
using namespace std;
#define MAXN 30010
int father[MAXN];
int rank[MAXN];
void make_set(int x)
{
    father[x]=x;
    rank[x]=0;
}
int find_set(int x)
{
    int t;
    if(x==father[x]) return x;
    else 
    {
        t=father[x];
        father[x]=find_set(father[x]);
        return father[x];
    }
}
void union_set(int x,int y)
{
    int rx=find_set(x);
    int ry=find_set(y);
    father[rx]=ry;
}
int main()
{
    int n,m;    
    while(scanf("%d%d",&n,&m)!=EOF)
    {
        if(n==0&&m==0) return 0;
        for(int i=0;i<=n;i++)
            make_set(i);
        int a,b;
        int sum;
        for(int i=1;i<=m;i++)
        {
            scanf("%d",&sum);
            if(sum>=1)
            {
                scanf("%d",&a);
                while(--sum)
                {
                    scanf("%d",&b);
                    int ra=find_set(a);
                    int rb=find_set(b);
                    if(ra!=rb)
                     union_set(a,b);
                }
            }
        }
        a=find_set(0);
        int ans=0;
        for(int i=0;i<=n;i++)
            if(a==find_set(i))
                ans++;
        printf("%d\n",ans);
    }
}