Submission #1097516

#	Time	Username	Problem	Language	Result	Execution time	Memory
1097516		alexander707070	Newspapers (CEOI21_newspapers)	C++14	52 / 100	142 ms	18692 KiB

newspapers

#include<bits/stdc++.h>
#define MAXN 600007
using namespace std;

int n,m,a,b,ver,cnt;
vector<int> v[MAXN];
vector<int> path;

bool dfs(int x,int p,int dep){
    if(dep==1)return true;
    
    for(int i:v[x]){
        if(i==p)continue;
        if(dfs(i,x,dep-1))return true;
    }

    return false;
}

void dfs2(int x,int p){
    if(cnt<ver)path.push_back(x);

    cnt++;

    for(int i:v[x]){
        if(i==p or v[i].size()==1)continue;
        dfs2(i,x);
        if(cnt<ver)path.push_back(x);
    }
}

int main(){

    cin>>n>>m;
    for(int i=1;i<=m;i++){
        cin>>a>>b;
        v[a].push_back(b);
        v[b].push_back(a);
    }

    if(m>n-1){
        cout<<"NO\n";
        return 0;
    }

    for(int i=1;i<=n;i++){
        if(v[i].size()<=2)continue;

        int br=0;
        for(int f:v[i]){
            if(dfs(f,i,3))br++;
        }

        if(br>2){
            cout<<"NO\n";
            return 0;
        }
    }

    cout<<"YES\n";
    if(n==1)cout<<"1\n1\n";
    else if(n==2)cout<<"2\n1 1\n";
    else{
        for(int i=1;i<=n;i++){
            if(v[i].size()>1)ver++;
        }

        ver=3*n;

        for(int i=1;i<=n;i++){            
            if(v[i].size()==1)continue;
            dfs2(i,0);

            cout<<path.size()*2<<"\n";
            for(int f:path)cout<<f<<" ";

            //reverse(path.begin(),path.end());
            for(int f:path)cout<<f<<" ";
            cout<<"\n";

            return 0;
        }
    }

    return 0;
}

• Subtask 1: 6 / 12
• Subtask 2: 6 / 8
• Subtask 3: 40 / 80