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;
}