并查集

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace  std;
const int N = 20010;
int p[N];
int n,m,q;
int find(int x)
{
    if (p[x]!=x) p[x]=find(p[x]);
    return p[x];
}
int main()
{
    scanf("%d%d",&n,&m);
    for (int i=1;i<=n;i++) p[i]=i;
    while (m--)
    {
        int a,b;
        scanf("%d%d",&a,&b);
        if (find(a)!=find(b))
            p[find(a)]=find(b);

    }
    scanf("%d",&q);
    while (q--)
    {
        int a,b;
        scanf("%d%d",&a,&b);
        if (find(a)==find(b)) puts("Yes");
        else puts("No");
    }
    return 0;
}