POJ 1611 The Suspects

　　简单的并查集的应用，统计和 0 联通的点的个数，约等于模板题。。。。。。手残没有判断两个点的根节点是否相等。。。。。贡献了五个WA......

#include <iostream>
#include <cstdlib>
#include <cstdio>

using namespace std;

int stu[30010],num[30010];

int find(int x)
{
    return stu[x] == x ? x : stu[x] = find(stu[x]);
}

void merge(int a,int b)
{
    int fa = find(a);
    int fb = find(b);
    if(fa != fb)
    {
        stu[fb] = fa;
        num[fa] += num[fb];
    }
}

int main()
{
    int n,m,s;

    int i,a,b;

    while(cin>>n>>m && (n||m))
    {
        for(i = 0;i <= n; ++i)
        {
            stu[i] = i;
            num[i] = 1;
        }
        for(i = 0;i < m; ++i)
        {
            cin>>s;
            if(s > 0)
                cin>>a;
            while(--s)
            {
                cin>>b;
                merge(a,b);
            }
        }

        cout<<num[find(0)]<<endl;
    }
    return 0;
}