hdu 1232 并查集

#include<iostream>
#include<cstdio>
using namespace std;

const int maxn=1005;
int f[maxn];
bool v[maxn];

int findset(int x){ return f[x] != x ? f[x]=findset(f[x]) : x;}

void merge(int a,int b)
{
    int fa=findset(a);
    int fb=findset(b);
    if(fa!=fb) f[fa]=fb;
}
int main()
{
    int n,m,i,a,b,ans;
    while(scanf("%d",&n),n)
    {
        scanf("%d",&m);
        for(i=1;i<=n;i++) f[i]=i,v[i]=false;
        while(m--)
        {
            scanf("%d %d",&a,&b);
            merge(a,b);
        }
        for(i=1;i<=n;i++) v[findset(f[i])]=true;
        ans=0;
        for(i=1;i<=n;i++) 
            if(v[i]) ans++;
        printf("%d\n",ans-1);
    }
    return 0;
}