1134. Vertex Cover (25)

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<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<set>
using namespace std;
const int maxm=10010;
struct node{
int u,v;
}edge[maxm];
int main()
{
int n,m;
scanf("%d%d",&n,&m);
for(int i=0;i<m;i++)
{
scanf("%d%d",&edge[i].u,&edge[i].v);
}
int k;
scanf("%d",&k);
for(int i=0;i<k;i++)
{
int nv,vi;
set<int> s;
scanf("%d",&nv);
for(int j=0;j<nv;j++)
{
scanf("%d",&vi);
s.insert(vi);
}
int num=0;
for(int j=0;j<m;j++)
{
int u=edge[j].u,v=edge[j].v;
if(s.find(u)!=s.end()||s.find(v)!=s.end())
{
num++;
}
}
if(num!=m)printf("No\n");
else printf("Yes\n");
}
return 0;
}