Submission #1084360

#	Time	Username	Problem	Language	Result	Execution time	Memory
1084360		onlk97	Newspapers (CEOI21_newspapers)	C++14	100 / 100	2 ms	604 KiB

newspapers

#include <bits/stdc++.h>
using namespace std;
int main(){
    int n,m;
    cin>>n>>m;
    if (m>=n){
        cout<<"NO\n";
        return 0;
    }
    if (n==1){
        cout<<"YES\n1\n1\n";
        return 0;
    }
    if (n==2){
        cout<<"YES\n2\n1 1\n";
        return 0;
    }
    vector <int> g[n+1];
    for (int i=1; i<=m; i++){
        int u,v; cin>>u>>v;
        g[u].push_back(v); g[v].push_back(u);
    }
    bool visited[n+1];
    int dist[n+1];
    queue <int> q;
    for (int i=1; i<=n; i++) visited[i]=0;
    visited[1]=1;
    dist[1]=0;
    q.push(1);
    while (!q.empty()){
        int tp=q.front(); q.pop();
        for (int i:g[tp]){
            if (!visited[i]){
                visited[i]=1;
                q.push(i);
                dist[i]=dist[tp]+1;
            }
        }
    }
    int u=max_element(dist+1,dist+n+1)-dist;
    for (int i=1; i<=n; i++) visited[i]=0;
    visited[u]=1;
    q.push(u);
    int bac[n+1];
    dist[u]=0;
    while (!q.empty()){
        int tp=q.front(); q.pop();
        for (int i:g[tp]){
            if (!visited[i]){
                visited[i]=1;
                q.push(i);
                dist[i]=dist[tp]+1;
                bac[i]=tp;
            }
        }
    }
    int v=max_element(dist+1,dist+n+1)-dist;
    for (int i=1; i<=n; i++) visited[i]=0;
    pair <int,int> d[n+1];
    for (int i=1; i<=n; i++) d[i]={0,0};
    int tp=v;
    while (tp!=u){
        d[tp]={tp,0};
        q.push(tp);
        visited[tp]=1;
        tp=bac[tp];
    }
    q.push(u);
    visited[u]=1;
    bool need[n+1];
    for (int i=1; i<=n; i++) need[i]=0;
    while (!q.empty()){
        int tp=q.front(); q.pop();
        for (int i:g[tp]){
            if (!visited[i]){
                visited[i]=1;
                q.push(i);
                d[i]={d[tp].first,d[tp].second+1};
                if (d[i].second>=2) need[tp]=1;
            }
        }
    }
    for (int i=1; i<=n; i++){
        if (d[i].second>=3){
            cout<<"NO\n";
            return 0;
        }
    }
    cout<<"YES\n";
    vector <int> vec;
    tp=bac[v];
    while (tp!=u){
        vec.push_back(tp);
        for (int i:g[tp]){
            if (d[i].first==tp&&need[i]){
                vec.push_back(i);
                vec.push_back(tp);
            }
        }
        tp=bac[tp];
    }
    vector <int> cpy=vec;
    reverse(cpy.begin(),cpy.end());
    for (int i:cpy) vec.push_back(i);
    cout<<vec.size()<<'\n';
    for (int i:vec) cout<<i<<' ';
    cout<<'\n'; 
}

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