POJ1611The Suspects

http://poj.org/problem?id=1611

这个题的话一看就知道是并查集，0号是已经被感染的，凡是与0号在一组的都是感染者

#include<cstdio>
#include<cstring>
#include<iostream>
using namespace std ;
int bing[30100],a[30100];
int findx(int x)
{
    int r = x ;
    while(bing[r] != r)
        r = bing[r] ;
    return r ;
}
int findy(int x)//递归往下找一组的
{
    if(x != bing[x])
        bing[x] = findy(bing[x]) ;
    return bing[x] ;
}
void merge(int x,int y)
{
    int fx,fy ;
    fx = findx(x) ;
    fy = findx(y) ;
    if(fx != fy)
    {
        if(a[fx] > a[fy])
        {
            bing[fy] = fx ;
            a[fx] += a[fy];
        }
        else
        {
            bing[fx] = fy ;
            a[fy] += a[fx] ;
        }
    }
}
int main()
{
    int n,m,x,y,count ;
    while(~scanf("%d %d",&m,&n))
    {
        if(m == 0&& n == 0) break ;
        for(int i = 0 ; i <= m-1 ; i++)

           {
               bing[i] = i ;
               a[i] = 1 ;
           }
        int s ;
        for(int i = 1 ; i <= n ; i++)
        {
            scanf("%d",&s) ;
            scanf("%d",&x) ;
            for(int j = 1 ; j <= s-1 ; j++)
            {
                scanf("%d",&y) ;
                merge(x,y) ;
            }
        }
        count = findy(0);
        printf("%d\n",a[count]);
    }
    return 0 ;
}