A1118 Birds in Forest [并查集]

#include<iostream>
#include<vector>
#include<map>
#include<string>
#include<cstring>
#include<cstdio>
#include<algorithm>
using namespace std;
const int maxn = 10002;
int father[maxn], cnt[maxn];
int getfather(int x)
{
	int a = x;
	while (x != father[x])
		x = father[x];
	while (a != father[a])
	{
		int z = a;
		a = father[a];
		father[z] = x;
	}
	return x;
}
void Union(int a, int b)
{
	int fa = getfather(a);
	int fb = getfather(b);
	if (fa != fb)
		father[fa] = fb;
}
bool exist[maxn];
int main()
{
	int n, k, temp1, temp2, queryn, treenum = 0, birdsnum = 0;
	cin >> n;
	for (int i = 0; i < maxn; i++)
		father[i] = i;
	for (int i = 0; i < n; i++)
	{
		cin >> k >> temp1;
		exist[temp1] = true;
		for (int j = 0; j < k - 1; j++)
		{
			cin >> temp2;
			exist[temp2] = true;
			Union(temp1, temp2);
		}
	}
	for (int i = 0; i < maxn; i++)
	{
		if (exist[i])
			cnt[getfather(i)]++;
	}
	for (int i = 0; i < maxn; i++)
	{
		if (cnt[i] != 0)
		{
			treenum++;
			birdsnum += cnt[i];
		}
	}
	cout << treenum << " " << birdsnum << endl;
	cin >> queryn;

	for (int i = 0; i < queryn; i++)
	{
		cin >> temp1 >> temp2;
		if (getfather(temp1) == getfather(temp2))
			cout << "Yes" << endl;
		else
			cout << "No" << endl;
	}
}