Submission #1114598

#	Time	Username	Problem	Language	Result	Execution time	Memory
1114598		vjudge1	Newspapers (CEOI21_newspapers)	C++17	8 / 100	2 ms	504 KiB

newspapers

#include<bits/stdc++.h>
using namespace std;
#define int long long
#define pb push_back
using pii=pair<int,int>;

int parent[5000];
int find(int i){
  if(parent[i]==i)return i;
  return parent[i]=find(parent[i]);
}
int unite(int i,int j){
  i=find(i);j=find(j);
  if(i==j)return 1;
  parent[i]=j;
  return 0;
}

signed main(){
  int n,m;
  cin>>n>>m;
  if(n==1){
    cout<<"YES\n1\n1";
    return 0;
  }
  for(int i=1;i<=n;i++)parent[i]=i;
  vector<int>v[n+1];
  for(int i=0;i<m;i++){
    int x,y;
    cin>>x>>y;
    v[x].pb(y);
    v[y].pb(x);
    if(unite(x,y)){
      cout<<"NO\n";
      return 0;
    }
  }
  int guy=0;
  for(int i=1;i<=n;i++){
    if(v[i].size()>2){
      guy=i;
    }
  }
  if(!guy){
    for(int i=1;i<=n;i++){
      if(v[i].size()==1){
        guy=v[i][0];
        break;
      }
    }
  }
  vector<int>chain;
  chain.pb(guy);
  while(1){
    int past=-1;
    if(1<chain.size())past=chain[chain.size()-2];
    int now=chain.back();
    for(int j:v[now]){
      if(j!=past&&v[j].size()>1){
        if(chain.back()!=now){
          cout<<"NO\n";
          return 0;
        }
        chain.pb(j);
      }
    }
    if(chain.back()==now){
      break;
    }
  }
  for(int i=1;i+1<chain.size();i++){
    for(int j:v[chain[i]]){
      if(j!=chain[i-1]&&j!=chain[i+1]&&v[j].size()>1){
        cout<<"NO\n";
        return 0;
      }
    }
  }
  cout<<"YES\n";
  vector<int>ans;
  for(int i=0;i<chain.size();i++){
    ans.pb(chain[i]);
  }
  for(int i=chain.size()-1;0<=i;i--){
    ans.pb(chain[i]);
  }
  cout<<ans.size()<<'\n';
  for(int i:ans)cout<<i<<' ';
}

Compilation message (stderr)

newspapers.cpp: In function 'int main()':
newspapers.cpp:71:18: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   71 |   for(int i=1;i+1<chain.size();i++){
      |               ~~~^~~~~~~~~~~~~
newspapers.cpp:81:16: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   81 |   for(int i=0;i<chain.size();i++){
      |               ~^~~~~~~~~~~~~

• Subtask 1: 0 / 12
• Subtask 2: 8 / 8
• Subtask 3: 0 / 80