原题目:
原题链接:https://www.patest.cn/contests/pat-a-practise/1134
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
题目大意
对于一个图,如果有一个集合,使得图中的任意一条边都至少存在一个端点在这个集合中,这个集合便可以为vertex cover。
输入图信息,N,M表示N个点M个边,依次输入M个边。
后K个集合,判断是否为vertex cover。
解题报告
先把边存起来,然后对于每个集合,遍历所有的边进行判断。
代码
1 | /* |