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;
}