hdu 1213 How Many Tables(并查集)

#include<iostream>
#include<stdio.h>
#include<string.h>
using namespace std;

#define MAXN 1024

int fa[MAXN];

int set_find(int d)
{
if(fa[d]<0)return d;
return fa[d]=set_find(fa[d]);
}

void set_join(int x,int y)
{
x=set_find(x);
y=set_find(y);
if(x!=y)fa[x]=y;
}

int main()
{
int T;
int N,M;
int A,B;
int sum;
scanf("%d",&T);
while(T--)
{
memset(fa,-1,sizeof(fa));
scanf("%d%d",&N,&M);
while(M--)
{
scanf("%d%d",&A,&B);
set_join(A,B);
}
sum=0;
for(int i=1; i<=N; ++i)
{
if(fa[i]<0)
{
++sum;
}
}
printf("%d\n",sum);
}
return 0;
}