hdu 1213 并查集

http://acm.hdu.edu.cn/showproblem.php?pid=1213

#include<iostream>#include<cstdio>using namespace std;#define N 1000int father[N];void ufset(){    for(int i=0;i<N;i++)        father[i]=-1;}int find(int x){    int s;    for(s=x;father[s]>=0;s=father[s]);    while(s!=x)    {        int tmp=father[x];        father[x]=s;        x=tmp;    }    return x;}void Union(int R1,int R2){    int r1=find(R1),r2=find(R2);    int tmp=father[r1]+father[r2];    if(father[r1]>father[r2])    {        father[r1]=r2;        father[r2]=tmp;    }    else    {        father[r2]=r1;        father[r1]=tmp;    }}int main(){    int n,sum,m,x,y;   // freopen("1.txt","r",stdin);    scanf("%d",&n);    while(n--)    {        int num=0;        scanf("%d%d",&sum,&m);        ufset();        for(int i=0;i<m;i++)         {             scanf("%d%d",&x,&y);             if(find(x)!=find(y))             {                Union(x,y);                 num++;             }         }         cout<<sum-num<<endl;    }}