Submission #519363

#	Time	Username	Problem	Language	Result	Execution time	Memory
519363		Keshi	Newspapers (CEOI21_newspapers)	C++17	100 / 100	56 ms	96076 KiB

newspapers

//In the name of God
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<ll, ll> pll;

const ll maxn = 2e6 + 100;
const ll mod = 1e9 + 7;
const ll inf = 1e18;

#define fast_io ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define file_io freopen("input.txt", "r+", stdin);freopen("output.txt", "w+", stdout);
#define pb push_back
#define Mp make_pair
#define F first
#define S second
#define Sz(x) ll((x).size())
#define all(x) (x).begin(), (x).end()

ll pw(ll a, ll b){
	ll c = 1;
	while(b){
		if(b & 1) c = c * a % mod;
		a = a * a % mod;
		b >>= 1;
	}
	return c;
}

int n, m;
namespace sub1{
int g[maxn], d[maxn], p[maxn], pp[maxn];
bool vis[maxn];
queue<int> q;

int get(int x){
	int y = 0;
	for(int i = 0; i < n; i++){
		if((x >> i) & 1) y |= g[i];
	}
	return y;
}
bool check(vector<int> vec){
	int v = (1 << n) - 1;
	for(int i : vec){
		v = get(v & (~(1 << i)));

		cout << i << "  ! ";
		for(int j = 0; j < n; j++){
			if((v >> j) & 1) cout << j << " ";
			else cout << "  ";
		}
		cout << "\n";
	}
	return (v == 0);
}

void solve(){

	for(int i = 0; i < m; i++){
		int v, u;
		cin >> v >> u;
		v--;
		u--;
		g[v] |= (1 << u);
		g[u] |= (1 << v);
	}
	p[(1 << n) - 1] = -1;
	vis[(1 << n) - 1] = 1;
	q.push((1 << n) - 1);
	while(!q.empty()){
		int v = q.front();
		q.pop();
		for(int i = 0; i < n; i++){
			int u = get(v & (~(1 << i)));
			if(!vis[u]){
				vis[u] = 1;
				d[u] = d[v] + 1;
				p[u] = v;
				pp[u] = i;
				q.push(u);
			}
		}
	}
	if(!vis[0]){
		cout << "NO\n";
		return;
	}
	cout << "YES\n";
	cout << d[0] << "\n";
	int v = 0;
	vector<int> vec;
	while(p[v] != -1){
		vec.pb(pp[v]);
		v = p[v];
	}
	reverse(all(vec));
	for(int i : vec){
		cout << i + 1 << " ";
	}
	return;
}
};

vector<int> gg[maxn], g[maxn], vec;
bool vvv;

void dfs(int v, int p = -1){
	if(vvv) vec.pb(v);
	vvv = 1;
	for(int u : g[v]){
		if(Sz(g[u]) == 1){
			vec.pb(u);
			vec.pb(v);
		}
	}
	for(int u : g[v]){
		if(Sz(g[u]) != 1 && u != p) dfs(u, v);
	}
	return;
}

int main(){
	fast_io;

	cin >> n >> m;
	if(m != n - 1){
		cout << "NO\n";
		return 0;
	}
	if(n <= 20){
		sub1::solve();
		return 0;
	}
	for(int i = 0; i < m; i++){
		int v, u;
		cin >> v >> u;
		gg[v].pb(u);
		gg[u].pb(v);
	}
	vector<int> ve2;
	for(int i = 1; i <= n; i++){
		if(Sz(gg[i]) == 1) continue;
		ve2.pb(i);
		for(int j : gg[i]){
			if(Sz(gg[j]) != 1) g[i].pb(j);
		}
	}
	if(Sz(ve2) == 1){
		cout << "YES\n2\n" << ve2[0] << " " << ve2[0] << "\n";
		return 0;
	}
	if(Sz(ve2) == 2){
		cout << "YES\n2\n" << ve2[0] << " " << ve2[1] << " " << ve2[1] << " " << ve2[0] << "\n";
		return 0;
	}
	int v = -1;
	for(int i = 1; i <= n; i++){
		if(Sz(g[i]) < 2) continue;
		int c = 0;
		for(int j : g[i]){
			if(Sz(g[j]) != 1) c++;
		}
		if(c > 2){
			cout << "NO\n";
			return 0;
		}
		if(c != 2) v = i;
	}
	dfs(v);
	vec.pop_back();
	vector<int> v2 = vec;
	reverse(all(v2));
	for(int i : v2){
		vec.pb(i);
	}
	cout << "YES\n";
	cout << Sz(vec) << "\n";
	for(int i : vec){
		cout << i << " ";
	}

	return 0;
}

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