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.
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 Mlines 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 [‘s are the indices of the vertices.
For each query, print in a line
Yesif the set is a vertex cover, orNoif not.
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
No Yes Yes No No
1 /* 2 Data: 2019-05-29 19:57:25 3 Problem: PAT_A1134#Vertex Cover 4 AC: 19:55 5 6 题目大意： 7 若图中各边连接的两个顶点，至少有一个顶点再集合中，称作这个顶点集为VC集 8 判断所给顶点集合是否为VC集 9 输入： 10 第一行给出，顶点数N和边数M，均<=1e4 11 接下来M行，给出顶点对 12 接下来一行，给出测试数K<=100 13 接下来K行，首先给出顶点数N，接下来N个数表示N个顶点 14 */ 15 16 #include<cstdio> 17 #include<algorithm> 18 const int M=1e4+10; 19 using namespace std; 20 struct node 21 { 22 int v1,v2; 23 }adj[M]; 24 int vis[M]; 25 26 int main() 27 { 28 #ifdef ONLINE_JUDGE 29 #else 30 freopen("Test.txt", "r", stdin); 31 #endif 32 33 int n,m,k,v,v1,v2; 34 scanf("%d%d", &n,&m); 35 for(int i=0; i<m; i++) 36 { 37 scanf("%d%d", &v1,&v2); 38 adj[i].v1=v1; 39 adj[i].v2=v2; 40 } 41 scanf("%d", &k); 42 while(k--) 43 { 44 scanf("%d", &v); 45 fill(vis,vis+M,0); 46 for(int i=0; i<v; i++){ 47 scanf("%d", &v1); 48 vis[v1]=1; 49 } 50 for(int i=0; i<m; i++){ 51 if(vis[adj[i].v1]==0 && vis[adj[i].v2]==0){ 52 vis[n]=1;break; 53 } 54 } 55 if(vis[n]) printf("No\n"); 56 else printf("Yes\n"); 57 } 58 59 return 0; 60 }
原文：https://www.cnblogs.com/blue-lin/p/10946532.html