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 1), 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 [ [
where Nv is the number of vertices in the set, and ['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
Nommp,看了半天都没有看懂题，英语弱到爆
百度后才知道，每条边至少有一个顶点存在set总，则该set是vertex cover
1 #include <iostream> 2 #include <vector> 3 using namespace std; 4 int a, b, n, m, k,nv; 5 int main() 6 { 7 cin >> n >> m; 8 vector<pair<int, int>>graph(m); 9 for (int i = 0; i < m; ++i) 10 cin >> graph[i].first >> graph[i].second; 11 cin >> k; 12 while (k--) 13 { 14 cin >> nv; 15 vector<bool>map(n, false); 16 while (nv--) 17 { 18 cin >> a; 19 map[a] = true; 20 } 21 bool flag = true; 22 for (int i = 0; flag&&i < m; ++i) 23 if (map[graph[i].first] == false && map[graph[i].second] == false)//没有一个顶点存在map中 24 flag = false; 25 cout << (flag ? "Yes" : "No") << endl; 26 } 27 return 0; 28 }