hdu 1213 (并查集)

题目链接

#include<string.h>
#include<stdio.h>
#include<stdlib.h>
int pre[30005];
int Find(int x)
{
    int r=x;
    while(r!=pre[r])
        r=pre[r];
    int i=x,j;
    while(pre[i]!=r)
    {
        j=pre[i];
        pre[i]=r;
        i=j;
    }
    return r;
}
void join(int x,int y)
{
    int fx=Find(x),fy=Find(y);
    if(fx!=fy)
    {
        pre[fx]=fy;
        //printf("fx=%d,fy=%d\n",fx,fy);
    }
}
int a[30003];
int t[3000];
int main()
{

    int n,m,T;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%d%d",&n,&m);
        int i,x,y,num;
        for(i=1;i<=n;i++)
            pre[i]=i;
        //printf("n=%d m=%d\n",n,m);
        while(m--)
        {
            scanf("%d%d",&x,&y);
            join(x,y);
        }
        memset(t,0,sizeof(t));
        for(i=1;i<=n;i++)
            t[Find(i)]=1;
        int ans=0;
        for(i=1;i<=n;i++)
            if(t[i])
            ans++;
        printf("%d\n",ans);

    }
}