hdu 1213 How Many Tables

#include<map>
#include<set>
#include<queue>
#include<cmath>
#include<vector>
#include<cstdio>
#include<string>
#include<cstring>
#include<cstdlib>
#include<iostream>
#include<algorithm>
#define  inf 0x0f0f0f0f

using namespace std;

const double pi=acos(-1.0);
const double eps=1e-8;
typedef pair<int,int>pii;

const int maxn=1000+10;

int p[maxn];
bool vis[maxn];
int find(int x){return (x==p[x]?x:p[x]=find(p[x]));}

int main()
{
    //freopen("in.txt","r",stdin);
    int t,n,m,x,y;
    scanf("%d", &t);
    while (t--)
    {
        scanf("%d%d",&n,&m);
        for (int i=0;i<=n;i++) p[i]=i;
        for (int i=0;i<m;i++)
        {
            scanf("%d%d",&x,&y);
            x=find(x);
            y=find(y);
            p[x]=y;
        }
        for (int i=1;i<=n;i++) p[i]=find(i);
        memset(vis,0,sizeof(vis));
        int ans=0;
        for(int i=1;i<=n;i++)
        if (!vis[p[i]])
        {
            ans++;
            vis[p[i]]=true;
        }
        printf("%d\n",ans);
    }
    //fclose(stdin);
    return 0;
}