POJ2524 并查集

#include<iostream>
using namespace std;
int father[50005];
int rank[50005];
int maxNum;

void make_set(int x){
     father[x]=x;
     rank[x]=1;
}

int find_set(int x){
     if(x!=father[x])
     {
         father[x]=find_set(father[x]);
     }
     return father[x];
}

void Union(int x,int y){
    x=find_set(x);
    y=find_set(y);
    if(x==y)  return;
    if(rank[x]<=rank[y]){
      father[x]=y;
      rank[y]+=rank[x];
      maxNum--;     //每合并一次总数减一
    }
    else{
      father[y]=x;
      rank[x]+=rank[y];
      maxNum--;
    }   
}

int main(){
    int m,n;
    int i,j;
    int x,y;
    int Case=1;
    freopen("acm.txt","r",stdin);
    cin>>n>>m;
   while(n){
       maxNum=n;
      for(i=n;i>0;i--)
        make_set(i);
      for(j=m;j>0;j--){
        cin>>x>>y;
        Union(x,y);
      }
      cout<<"Case "<<Case<<": "<<maxNum<<endl;
      cin>>n>>m;
      Case++;
      }
    return 0;
}