A1118 Birds in Forest (25 分)

#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <set>
using namespace std;
const int inf = (1 << 31) - 10;
const int maxn = 10010;
int N, Q;
int root[maxn], bird[maxn];

int find(int x){
	if(x == root[x]) return x;
	return root[x] = find(root[x]);
}
void unite(int x, int y){
	int rx = find(x);
	int ry = find(y);
	if(rx != ry) root[rx] = ry;
}
int main() {
	//freopen("3.txt", "r", stdin);	
	for(int i = 1; i < maxn; i++){
		root[i] = i;
	}
	memset(bird, 0, sizeof(bird)); 
	scanf("%d", &N);
	int K, no, num = 0, tempRoot;
	for(int i = 0; i < N; i++){
	 	scanf("%d", &K);
	 	for(int j = 0; j < K; j++){
	 		scanf("%d", &no);
	 		if(!bird[no]){
	 			num++;
	 			bird[no] = 1;
			}
	 		if(j == 0){
	 			tempRoot = no;
				 continue;	
			} 
	 		if(root[no] == no){
	 			root[no] = tempRoot;
			}else{
			 	unite(tempRoot, root[no]);
			}
		 }
	}
	scanf("%d", &Q);
	int tree = 0, b1, b2, r;
	int used[maxn];
	memset(used, 0, sizeof(used));
	for(int i = 1; i <= num; i++){
		r = find(i);
		if(used[r] == 0){
			tree++;
			used[r] = 1;
		}
	}
	printf("%d %d\n", tree, num);
	for(int i = 0; i < Q; i++){
		scanf("%d %d", &b1, &b2);
		if(find(b1) == find(b2)){
			printf("Yes\n");
		}else{
			printf("No\n");
		}
	}
	return 0;
}