1134 Vertex Cover

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 104), 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:

Nv​ v[1] v[2]⋯v[Nv​]

where Nv​ 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

#include 
#include 
#include 
using namespace std;
 
struct edge {
	int u, v;
} a[10010];
int n, m, k, s, v[10010];
bool vis[10010];
 
int main() {
	cin >> n >> m;
	for (int i = 0; i < m; i++) {
		cin >> a[i].u >> a[i].v;
	}
	cin >> k;
	while (k--) {
		cin >> s;
		bool flag = 0;
		memset(vis, 0, sizeof(vis));
		for (int i = 0; i < s; i++) {
			cin >> v[i];
			vis[v[i]] = 1;
		}
		for (int i = 0; i < m; i++) {
			if (!vis[a[i].u] && !vis[a[i].v]) {
				flag = 1;
				break;
			}
		}
		if (!flag) {
			cout << "Yes" << endl;
		} else {
			cout << "No" << endl;
		}
	}
	return 0;
}