Submission #497213

#	Time	Username	Problem	Language	Result	Execution time	Memory
497213		Victor	Newspapers (CEOI21_newspapers)	C++17	52 / 100	2 ms	460 KiB

newspapers

// #pragma GCC target ("avx,avx2,fma")
// #pragma GCC optimize ("Ofast,inline") // O1 - O2 - O3 - Os - Ofast
// #pragma GCC optimize ("unroll-loops")
#include <bits/stdc++.h>

using namespace std;

#define rep(i, a, b) for (int i = (a); i < (b); ++i)
#define per(i, a, b) for (int i = (b - 1); i >= (a); --i)
#define trav(a, x) for (auto &a : x)

#define all(x) x.begin(), x.end()
#define sz(x) x.size()
#define pb push_back
#define debug(x) cout << #x << " = " << x << endl

#define umap unordered_map
#define uset unordered_set

typedef pair<int, int> ii;
typedef pair<int, ii> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<vi> vvi;

typedef long long ll;
typedef pair<ll, ll> pll;
typedef vector<ll> vll;
typedef vector<pll> vpll;

const int INF = 1'000'000'007;

vi graph[1001];
int n, m, cnt, start;
vi ans;

bool dfs(int u, int p, int dist) {
    //cout<<"u = "<<u+1<<" p = "<<p+1<<" dist = "<<dist<<endl;
    if (dist == 3) return 1;
    trav(v, graph[u]) if (v != p) {
        bool val = dfs(v, u, dist + 1);
        if(u==start)cnt+=val;
        else if(val)return 1;
    } 
    return 0;
}

void solve(int u,int p, bool parity){
    vi small, big;
    trav(v,graph[u])if(v!=p){
        if(dfs(v,u,1))big.pb(v);
        else small.pb(v);
    }

    assert(sz(big)<3);
    if(!big.empty())solve(big[0], u, parity^1);
    trav(v,small){
        if(sz(ans) % 2 == parity)ans.pb(u);
        ans.pb(v);
    }

    if(sz(ans) % 2 == parity)ans.pb(u);

    if(sz(big)==2)solve(big[1], u, parity^1);
}

int main() {
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);

    cin >> n >> m;
    if (m >= n) {
        cout << "NO" << endl;
        return 0;
    }

    while (m--) {
        int u, v;
        cin >> u >> v;
        graph[--u].pb(--v);
        graph[v].pb(u);
    }

    rep(i, 0, n) {
        cnt = 0;
        start=i;
        dfs(i, i, 0);
        //cout << "u = " << i + 1 << " cnt = " << cnt << endl;
        if (cnt >= 3) {
            cout << "NO" << endl;
            return 0;
        }
    }

    start = cnt = 0;
    dfs(0,0,0);
    solve(0,0,0);
    
    cout<<"YES"<<endl;
    cout<<sz(ans)*2+1-(sz(ans)%2)<<endl;
    trav(u,ans)cout<<u+1<<' ';
    if(sz(ans)%2==0)cout<<"1 ";
    trav(u,ans)cout<<u+1<<' ';
    cout<<endl;
    return 0;
}

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