1118 Birds in Forest (25 分) （并查集

添加链接描述

#include<bits/stdc++.h>
using namespace std;
const int N=1e4+9;
int fa[N];
int find(int x){
    if(x==fa[x])return fa[x];
    return fa[x]=find(fa[x]);
}
void merge(int x,int y){
    x=find(x),y=find(y);
    if(x!=y)fa[y]=x;
}
int vis[N],cnt[N],birds,trees;
int main(){
    int n;
    cin>>n;
    for(int i=1;i<=1e4;i++)fa[i]=i;
    for(int i=1;i<=n;i++){
        int k,id;
        cin>>k;
        if(k)cin>>id,k--;
        vis[id]=1;
        while(k--){
            int x;
            cin>>x;
            merge(x,id);
            vis[x]=1;
        }
    }
    for(int i=1;i<=1e4;i++){
        if(vis[i]){
            int p=find(i);//先合并 然后再来一次统计当前的统计的群落
            cnt[p]++;
            // cout<<p<<endl;
        }
    }
    for(int i=1;i<=1e4;i++){
        if(vis[i])birds++;
        if(cnt[i]){
            trees++;
        }
    }
    printf("%d %d\n",trees,birds);
    int q;
    cin>>q;
    while(q--){
        int a,b;
        cin>>a>>b;
        if(find(a)!=find(b)){
            cout<<"No"<<endl;
        }
        else cout<<"Yes"<<endl;
    }
    return 0;
}

标签：vis,int,查集,cin,find,fa,id,1118,Birds
来源： https://blog.csdn.net/Minelois/article/details/123034587