並查集的模板題：

#include<iostream>
#include<cstdio>
using namespace std;
const int maxn = 2e4+5;
int fa[maxn];
int find(int x)
{
    return fa[x] == x ? x : fa[x] = find(fa[x]);
}
void unite(int x, int y)
{
    int x1 = find(x);
    int y1 = find(y);
    if (x1 != y1)fa[x1] = y1;
}
int main()
{
    
 
int n, m, x, y;
    scanf("%d%d", &n, &m);
    for (int i = 1; i <= n; ++i)fa[i] = i;
    while (m--)
    {
        scanf("%d%d", &x, &y);
        unite(x, y);
    }
    scanf("%d", &m);
    while (m--)
    {
        scanf("%d%d", &x, &y);
        if (find(x) == find(y))printf("
 
Yes\n");
        else printf("No\n");
    }
}