Submission #926199

#	Time	Username	Problem	Language	Result	Execution time	Memory
926199		GrindMachine	Newspapers (CEOI21_newspapers)	C++17	50 / 100	50 ms	8796 KiB

newspapers

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) (int)a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x,y) ((x+y-1)/(y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "YES" << endl
#define no cout << "NO" << endl

#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i)
#define rev(i,s,e) for(int i = s; i >= e; --i)
#define trav(i,a) for(auto &i : a)

template<typename T>
void amin(T &a, T b) {
    a = min(a,b);
}

template<typename T>
void amax(T &a, T b) {
    a = max(a,b);
}

#ifdef LOCAL
#include "debug.h"
#else
#define debug(x) 42
#endif

/*



*/

const int MOD = 1e9 + 7;
const int N = 1e3 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;

vector<ll> adj[N];
vector<ll> mx_depth(N);
vector<ll> par(N);
vector<ll> nxt(N);
bool ok = true;

void dfs1(ll u, ll p){
    mx_depth[u] = 0;
    nxt[u] = -1;
    par[u] = p;

    trav(v,adj[u]){
        if(v == p) conts;
        dfs1(v,u);
        amax(mx_depth[u],mx_depth[v]+1);
    }

    vector<ll> big;

    trav(v,adj[u]){
        if(v == p) conts;
        if(mx_depth[v] > 1){
            big.pb(v);
        }
    }

    if(sz(big) > 1){
        ok = false;
    }
    else{
        if(sz(big) == 1){
            nxt[u] = big[0];
        }
    }
}

vector<ll> curr_ans;

void dfs2(ll u, ll p){
    trav(v,adj[u]){
        if(v == p) conts;
        if(v != nxt[u]){
            curr_ans.pb(u);
            curr_ans.pb(v);
        }
    }

    if(nxt[u] == -1) return;

    ll v = nxt[u];
    pll best = {-inf2,-inf2};

    trav(w,adj[v]){
        if(w == u) conts;
        curr_ans.pb(w);
        curr_ans.pb(v);
        pll px = {mx_depth[w],w};
        amax(best,px);
    }

    assert(best.ss != -inf2);
    dfs2(best.ss,v);
}

void solve(int test_case)
{
    ll n,m; cin >> n >> m;
    rep1(i,m){
        ll u,v; cin >> u >> v;
        adj[u].pb(v), adj[v].pb(u);
    }

    if(m != n-1){
        no;
        return;
    }

    if(n == 1){
        yes;
        cout << 1 << endl << 1 << endl;
        return;
    }

    vector<ll> ans;

    rep1(i,n){
        ok = true;
        dfs1(i,-1);
        
        if(ok){
            curr_ans.clear();
            dfs2(i,-1);
            curr_ans.pb(1);
            dfs2(i,-1);
            if(ans.empty()){
                ans = curr_ans;
            }
            else{
                if(sz(curr_ans) < sz(ans)){
                    ans = curr_ans;
                }
            }
        }
    }

    if(ans.empty()){
        no;
        return;
    }

    yes;
    assert(sz(ans) <= 5*n);
    cout << sz(ans) << endl;
    trav(x,ans) cout << x << " ";
    cout << endl;


    // yes;
    // vector<ll> ans;
    // for(int i = 2; i <= n; ++i){
    //     ans.pb(i);
    // }
    // if(!((n-1)&1)){
    //     ans.pb(1);
    // }
    // for(int i = 2; i <= n; ++i){
    //     ans.pb(i);
    // }

    // cout << sz(ans) << endl;
    // trav(x,ans) cout << x << " ";
    // cout << endl;
}

int main()
{
    fastio;

    int t = 1;
    // cin >> t;

    rep1(i, t) {
        solve(i);
    }

    return 0;
}

• Subtask 1: 6 / 12
• Subtask 2: 4 / 8
• Subtask 3: 40 / 80