hdu 1213 How Many Tables 并查集模板题+路径压缩

#include <iostream>
#include<cstdio>
#include<cmath>
#include<cstring>

using namespace std;

int pre[1100];

int findset(int v)
{
int t1,t2=v;
while(v!=pre[v])    v=pre[v];
while(t2!=pre[t2])
{
t1=pre[t2];
pre[t2]=v;
t2=t1;
}
return v;
}

void unions(int x,int y)
{
int t1=findset(x);
int t2=findset(y);
if(t1!=t2)  pre[t1]=t2;
}

int main()
{
int T,n,m;
cin>>T;
while(T--)
{
cin>>n>>m;
for(int i=1;i<=n;i++)   pre[i]=i;
for(int i=0;i<m;i++)
{
int u,v;
scanf("%d%d",&u,&v);
unions(u,v);
}
int ans=0;
for(int i=1;i<=n;i++)
if(pre[i]==i)   ans++;
cout<<ans<<endl;

}
}