1134 Vertex Cover （25 分）

A vertex cover of a graph is a set of vertices such that each edge of the graph is incident to at least one vertex of the set. Now given a graph with several vertex sets, you are supposed to tell if each of them is a vertex cover or not.

Input Specification:

Each input file contains one test case. For each case, the first line gives two positive integers N and M (both no more than 10​4​​), being the total numbers of vertices and the edges, respectively. Then M lines follow, each describes an edge by giving the indices (from 0 to N−1) of the two ends of the edge.

After the graph, a positive integer K (≤ 100) is given, which is the number of queries. Then K lines of queries follow, each in the format:

N​v​​ v[1] v[2]⋯v[N​v​​]

where N​v​​ is the number of vertices in the set, and v[i]'s are the indices of the vertices.

Output Specification:

For each query, print in a line Yes if the set is a vertex cover, or No if not.

Sample Input:

10 11
8 7
6 8
4 5
8 4
8 1
1 2
1 4
9 8
9 1
1 0
2 4
5
4 0 3 8 4
6 6 1 7 5 4 9
3 1 8 4
2 2 8
7 9 8 7 6 5 4 2

Sample Output:

No
Yes
Yes
No
No

正月初一，新年第一篇^-^

#include<iostream>
#include<vector> 
using namespace std;
int main(){
	int n,m;
	cin >> n >> m;
	vector<int> v[n+1];
	for(int i = 0;i < m;i++){
		int a,b;
		cin >> a >> b;
		v[i].push_back(a);
		v[i].push_back(b);
	}
	int k;
	cin >> k;
	for(int j = 0;j < k;j++){
		vector<int> book(m+1,0);
		int cnt;
		cin >> cnt;
		for(int i = 0;i < cnt;i++){
			int a;
			cin >> a;
			book[a] = 1;
		}
		int num=0;
		for(int i = 0;i < m;i++){
			if(book[v[i][0]] == 1 || book[v[i][1]] == 1){
				++num;
			}else{
				break;
			}
		}
		if(num == m){
			cout << "Yes" << endl;
		}else{
			cout << "No" << endl;
		}
	}
	return 0;
}