1134 Vertex Cover (25 分)

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 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:

N​v​​ [ [

where N​v​​ 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
No


给n个结点m条边，再给k个集合。对这k个集合逐个进行判断。每个集合S里面的数字都是结点编号，
求问整个图所有的m条边两端的结点，是否至少一个结点出自集合S中。如果是，输出Yes否则输出No

直接存是第几条边就行，然后用个set

#include <bits/stdc++.h>
using namespace std;
int n,m,k,p;
vector<int> v[10005];
set<int> s;
int main(){
    cin >> n >> m;
    int x,y;
    for(int i = 1; i <= m; i++){
        cin >> x >> y;
        v[x].push_back(i);
        v[y].push_back(i);
    }
    cin >> k;
    while(k--){
        cin >> p;
        set<int> st;
        for(int i = 0; i < p; i++){
            cin >> x;
            for(int j = 0; j < v[x].size(); j++){
                st.insert(v[x][j]);
            }
        }
        if(st.size() == m){
            cout <<"Yes"<<endl;
        }else{
            cout <<"No"<<endl;
        }
    }
    return 0;
}