Submission #718056

#	Time	Username	Problem	Language	Result	Execution time	Memory
718056		baokhue232005	Newspapers (CEOI21_newspapers)	C++14	50 / 100	2 ms	516 KiB

newspapers

/*
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimize("unroll-loops")
*/
// lethal option

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

#define all(flg) flg.begin(), flg.end()
#define int long long
#define pb push_back
#define fi first
#define se second
#define endl "\n"
#define eb emplace_back
#define ii pair<int, int>
#define vi vector<int>
#define PI 3.141592653589793238462643383279502884
#define ll long long
#define ld long double
#define for1(i, ff, gg) for(int i = ff; i <= gg; ++i)
#define for2(i, ff, gg) for(int i = ff; i >= gg; --i)
const ll mod = 1e9 + 7;
const int maxN = 1005;
const ll oo = 1e18 + 7;
int n, a[maxN];
int x, y, z, k;

vi vc[maxN];
void die(){
    cout << "NO\n"; exit(0);
}

void win(vi ans){
    cout << "YES\n";
    if(ans.size() > 1) ans.erase(ans.begin());
    if(ans.size() > 1) ans.pop_back();
    cout << ans.size() * 2 << endl;
    for1(dumb, 0, 1){
        reverse(all(ans));
        for(int cc : ans) cout << cc << " ";
    }
    cout << endl;
    exit(0);
}

int chi[maxN];

vi steak[maxN];
int used[maxN];

vi ans;

void dfs(int node){
    used[node] = 1;
    ans.pb(node);
    for(int cc : steak[node]){
        ans.pb(cc);
        ans.pb(node);
    }
    for(int cc : vc[node]) if(!used[cc]) dfs(cc);
}

signed main(){
    // freopen(".inp", "r", stdin);
    ios_base::sync_with_stdio(0);
    cin.tie(NULL);
    cout.tie(NULL);
    cin >> n >> z;
    if(n <= 2){
        cout << "YES\n";
        cout << n << endl;
        while(n--) cout << "1 ";
        cout << endl;
        exit(0);
    }
    if(z >= n) die();
    for1(i, 2, n){
        cin >> x >> y;
        vc[x].pb(y);
        vc[y].pb(x);
    }
    for1(i, 1, n) chi[i] = vc[i].size();
    memset(used, 0, sizeof(used));
    for1(dumb, 0, 1){
        vi cac;
        if(dumb == 1){
            vi sex;
            for1(i, 1, n) if(!used[i]) sex.pb(i);
            sex.insert(sex.begin(), 0);
            sex.pb(0);
            if(sex.size() <= 2) win(sex);
        }
        for1(i, 1, n) steak[i].clear();
        for1(i, 1, n) if(!used[i] && chi[i] == 1) cac.pb(i);
        for(int node : cac) if(chi[node] == 1){
            for(int cc : vc[node]) if(!used[cc]){
                steak[cc].pb(node);
                --chi[cc];
                used[node] = 1;
            }
        }
    }
    for1(i, 1, n) if(!used[i] && chi[i] >= 3) die();
    for1(i, 1, n) if(!used[i] && chi[i] <= 1){
        dfs(i);
        win(ans);
    }
}

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