poj 2524 求连通分量（并查集模板题）

求连通分量

Sample Input

10 9
1 2
1 3
1 4
1 5
1 6
1 7
1 8
1 9
1 10
10 4
2 3
4 5
4 8
5 8
0 0
Sample Output

Case 1: 1
Case 2: 7

# include <iostream>
# include <cstdio>
# include <cstring>
# include <algorithm>
# include <cmath>
# include <queue>
# define LL long long
using namespace std ;

const int MAXN = 50010;
int F[MAXN];
int num[MAXN] ;

int find(int x)//找x的祖先结点
{
    if(F[x]==x) return x;
    return F[x]=find(F[x]);
}
void bing(int u,int v) //按秩合并
{
    int x = find(u);
    int y = find(v);
    if(x == y)
        return ;
    if(num[x] >= num[y])
    {
        F[y] = x;
        num[x] += num[y];
    }
    else
    {
        F[x] = y;
        num[y] += num[x];
    }
}
int main()
{
    //freopen("in.txt","r",stdin) ;
    int n , m ;
    int Case = 0 ;
    while(scanf("%d %d", &n , &m) != EOF)
    {
         Case++ ;
         if (n == 0 && m == 0)
             break ;

         int i ;
         for(i = 1 ; i <= n ; i++)
         {
             F[i] = i ;
             num[i] = 1 ;
         }
        int u , v ;
        while(m--)
        {
            scanf("%d %d" , &u , &v) ;
            bing(u , v) ;

        }
        int res = 0 ;
        for(i = 1 ; i <= n ; i++)
            if (F[i] == i)
               res++ ;
        printf("Case %d: %d
" , Case , res) ;
    }
    return 0;
}