hdu 2473 Junk-Mail Filter 并查集

#include <stdio.h>
#include <string.h>
#define maxn 1001000
int id[maxn],p[maxn];
bool vis[maxn];
int find(int x)
{
    if(p[x]==x) return x;
    else return p[x]=find(p[x]);
}
void link(int a,int b)
{
    int x=find(a);
    int y=find(b);
    if(x!=y)
        p[x]=y;
}
int main()
{
    int n,m;
    int x,y;
    int sum=0;
    int cnt,i;
    while(1)
    {
        scanf("%d%d",&n,&m);
        cnt=n;
        char c;
        sum++;
        if(n==0&&m==0) break;
        for(i=0;i<maxn;i++)
            p[i]=id[i]=i;
        for(i=1;i<=m;i++)
        {
            getchar();
            scanf("%c",&c);
            if(c=='M')
            {
                scanf("%d%d",&x,&y);
                link(id[x],id[y]);
            }
            else
            {
                scanf("%d",&x);
                id[x]=cnt++;
            }
        }

        int ans=0;
        memset(vis,0,sizeof(vis));
        for(i=0;i<n;i++)
        {
            x=find(id[i]);
            if(vis[x]==0)
            {
                vis[x]=1;
                ans++;
            }
        }
        printf("Case #%d: %d
",sum,ans);
    }
}