PAT (Advanced Level) Practice 1134 Vertex Cover (25 分) set
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 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
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
題意:
給出一些頂點,判斷是否這些頂點的邊能否包含全部的邊。
stl中 set的使用。
程式碼如下:
#include <cstdio> #include <cstring> #include <algorithm> #include <iostream> #include <vector> #include <queue> #include <map> #include <set> using namespace std; const int maxn=1e4+5; int n,m,k; map<int,vector<int> >ma; int a[1005]; int main() { scanf("%d%d",&n,&m); for (int i=0;i<m;i++) { int x,y; scanf("%d%d",&x,&y); ma[x].push_back(i); ma[y].push_back(i); } scanf("%d",&k); while (k--) { int l; scanf("%d",&l); set<int>se; for (int i=0;i<l;i++) { int x; scanf("%d",&x); for (int j=0;j<ma[x].size();j++) { se.insert(ma[x][j]); } } if(se.size()==m) { printf("Yes\n"); } else { printf("No\n"); } } return 0; }