poj 1611 The Suspects(并查集)

#include<iostream>
#include<stdio.h>
#include<string.h>
using namespace std;

#define MAXN 30005

int fa[MAXN];
int set_find(int d)
{
    if(fa[d]<0)return d;
    return fa[d]=set_find(fa[d]);
}
void set_join(int x,int y)
{
    x=set_find(x);
    y=set_find(y);
    if(x!=y)fa[x]=y;
}
int main()
{
    int n,m,k;
    int x,y;
    int fa0;//节点0的父节点
    int sum;//
    while(~scanf("%d%d",&n,&m))
    {
        if(n==0&&m==0)break;
        memset(fa,-1,sizeof(fa));
        for(int i=0; i<m; ++i)
        {
            scanf("%d",&k);
            scanf("%d",&x);
            for(int j=1; j<k; ++j)
            {
                scanf("%d",&y);
                set_join(x,y);
            }
        }
        fa0=set_find(0);
        sum=0;
        for(int i=0; i<n; ++i)
        {
            if(set_find(i)==fa0)
            {
                ++sum;
            }
        }
        printf("%d\n",sum);
    }
    return 0;
}