PAT甲级-1118 Birds in Forest (25 分)

题目：1118 Birds in Forest (25 分)

分析：并查集，和1107 social cluster很像，本题要在findFa函数中进行路径压缩，否则有一个测试点会超时，并查集还是要多练，太菜了

#include <iostream>
#include<cstring>
#include<vector>
#include<map>
#include<math.h>
#include<stdio.h>
#include<math.h>
#include<algorithm>
using namespace std;
#define MAX 999999999
int n,m,k;
int fa[10001];
int bird[10001];
int ans[10001];
int findFa(int x)
{
    
    
    if(x == fa[x]) return x;
    return fa[x] = findFa(fa[x]);
}
void uni(int a,int b)
{
    
    
    fa[findFa(a)] = findFa(b);
}
int main()
{
    
    
    cin>>n;
    for(int i = 1; i <= 10001;i++)
        fa[i] = i;
    int num = 0;
    for(int i = 1; i <= n ;i++)
    {
    
    
        int k;scanf("%d",&k);
        int fro ;
        for(int j = 0; j < k ; j++)
        {
    
    
            int x;scanf("%d",&x);
            if(j == 0)
                fro = x;
            else
                uni(x,fro);
            if(bird[x] == 0) num++;
            bird[x] = 1;
        }
    }
    int cnt = 0;
    for(int i = 1; i <= 10001;i++)
        if(fa[i] == i && bird[i] == 1)
            cnt++;
    cout<<cnt<<" "<<num<<endl;
    cin>>k;
    for(int i = 0 ; i < k ;i++)
    {
    
    
        int a,b;cin>>a>>b;
        if(findFa(a) == findFa(b))
            cout<<"Yes\n";
        else
            cout<<"No\n";
    }
    return 0;
}