PAT (Advanced Level) Practise1134Vertex Cover (25)

1134. Vertex Cover (25)

时间限制

600 ms

内存限制

65536 kB

代码长度限制

16000 B

判题程序

Standard

作者

CHEN, Yue

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:

10 118 76 84 58 48 11 21 49 89 11 02 454 0 3 8 46 6 1 7 5 4 93 1 8 42 2 87 9 8 7 6 5 4 2

Sample Output:

NoYesYesNoNo

#include<stdio.h>const int N = 1e5 + 10;int n, m, q, x, y;int a[N], b[N], c[N];int main(){  scanf("%d%d",&n,&m);  for (int i = 0;i<m;i++) {    scanf("%d%d",&a[i],&b[i]);  }  scanf("%d",&q);  while (q--) {    scanf("%d",&x);    for (int i = 0;i<n;i++) c[i] = 0;    while (x--) scanf("%d",&y),c[y] = 1;    int flag = 1;    for (int i = 0;i<m;i++) {      if(c[a[i]]+c[b[i]]) continue;      flag = 0; break;    }    puts(flag?"Yes":"No");  }  return 0;}