poj 1611

并查集的入门题吧，了解了简单的思想~~~

#include <iostream>
#include <string>
#include <vector>
#include <cstdlib>
#include <cmath>
#include <map>
#include <algorithm>
#include <list>
#include <ctime>
#include <set>
#include <string.h>
#include <queue>
#include <cstdio>
#define CLR(arr, what) memset(arr, what, sizeof(arr))
typedef long long ll;
const int MAX = 100000;
using namespace std;


int n, m, i, j;
int father[30005], num[30005];

void makeSet(int n)
{
    for(i = 0; i < n; i++)
    {
        father[i] = i; //使用本身做根
        num[i] = 1;
    }
}
int findSet(int x)
{
    if(father[x] != x) //合并后的树的根是不变的
    {
        father[x] = findSet(father[x]);
    }
    return father[x];
}

void Union(int a, int b)
{
    int x = findSet(a);
    int y = findSet(b);
    if(x == y)
    {
        return;
    }
    if(num[x] <= num[y])
    {
        father[x] = y;
        num[y] += num[x];
    }
    else
    {
        father[y] = x;
        num[x] += num[y];
    }
}

int main()
{
    while(scanf("%d %d", &n, &m)!=EOF && n != 0)
    {
        makeSet(n);
        for(i = 0; i < m; i++)
        {
            int count, first, b;
            scanf("%d %d",&count, &first);
            for(j = 1; j < count; j++)
            {
                scanf("%d",&b);
                Union(first,b);
            }
        }
        printf("%d\n",num[findSet(0)]);
    }
    return 0;
}

from kakamilan