RT，代码如下

#include <bits/stdc++.h>
using namespace std;
int n, m, p, x, y, fa[5010];

int find (int x) {
	if (x == fa[x])
		return x;
	return fa[x] = find(fa[x]);
}

void join(int c1, int c2) {
	int f1 = find(c1), f2 = find(c2);
	if (f1 != f2)
		fa[f1] = f2;
}

int main() {
	cin >> n >> m >> p;
	for (int i = 1; i <= n; i++)
		fa[i] = i;
	for (int i = 0; i < m; i++) {
		cin >> x >> y;
		join(x, y);
	}
	for (int i = 0; i < p; i++) {
		cin >> x >> y;
		if (find(x) == find(y))
			cout << "YES" << endl;
		else
			cout << "NO" << endl;
	}
	return 0;
}