第十四届华中科技大学程序设计竞赛 C.Professional Manager(并查集操作)

#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
using namespace std;
const int MAXN = 200005;
int n,m,T,ans,num;
int pre[MAXN],box[MAXN],siz[MAXN];

void init(){
  for(int i=0;i<=MAXN;i++){
    pre[i] = i;
    box[i] = i;
    siz[i] = 1;
  }
}

int Find(int x){
  if(box[x] != x){
    box[x] = Find(box[x]);
  }
  return box[x];
}

void merge(int x,int y){
  int fx = Find(x);
  int fy = Find(y);
  if(fx != fy){
    box[fy] = fx;
    siz[fx] += siz[fy];
    // siz[fy] = 0;
  }
}

int main()
{
  int Case = 1;
  scanf("%d",&T);
  while(T--){
    init();
    scanf("%d%d",&n,&m);
    num = n + 1;
    printf("Case #%d:\n",Case++);
    while(m--){
      scanf("%d",&ans);
      if(ans == 1){
        int a,b;
        scanf("%d%d",&a,&b);
        merge(pre[a],pre[b]);
      }
      else if(ans == 2){
        int a;
        scanf("%d",&a);
        siz[Find(pre[a])]--;        // 该森林中少一个树
        pre[a] = num;
        num++;
      }
      else if(ans == 3){
        int a;
        scanf("%d",&a);
        printf("%d\n",siz[Find(pre[a])]);
      }
      else{
        int a,b;
        scanf("%d%d",&a,&b);
        if(Find(pre[a]) != Find(pre[b]))printf("NO\n");
        else printf("YES\n");
      }
    }
  }
  return 0;
}