Submission #626728

#	Time	Username	Problem	Language	Result	Execution time	Memory
626728		iomoon191	Newspapers (CEOI21_newspapers)	C++17	54 / 100	3 ms	2772 KiB

newspapers

#include <bits/stdc++.h>
#define sz(x) (int)(x).size()
#define all(x) x.begin(), x.end()
#define For(i, a, b) for(int i = a; i <= b; i++)
#define roF(i, a, b) for(int i = a; i >= b; i--)
using namespace std;
using ll = long long;
using pi = pair<int, int>;
const int N = 1e5 + 5;
const int inf = 0x3f3f3f3f;
// #define int ll

int n, m, par[N];
vector<int> adj[N];
bool ok[N], used[N];

pi dfs(int u, int p = -1){
	pi ret(0, u);
	for(auto &v : adj[u]){
		if(v == p) continue;
		par[v] = u;
		pi i = dfs(v, u); i.first++;
		ret = max(ret, i);
	}
	return ret;
}

void rmain(){
	cin >> n >> m;
	if(m != n - 1){ cout << "NO"; return; }
	if(n == 1){ cout << "YES\n1\n1"; return; }
	if(n == 2){ cout << "YES\n2\n1 1"; return; }
	For(i, 1, m){
		int u, v; cin >> u >> v;
		adj[u].push_back(v);
		adj[v].push_back(u);
	}
	int f = dfs(1).second;
	int s = dfs(f).second;
	for(int i = s; ; i = par[i]){
		ok[i] = 1; used[i] = 1;
		for(auto &j : adj[i]){
			ok[j] = 1;
			for(auto &k : adj[j]) ok[k] = 1;
		}
		if(i == f) break;
	}
	if(count(ok + 1, ok + n + 1, 0)){
		cout << "NO"; return;
	}
	vector<int> res;
	for(int i = par[s]; i != f; i = par[i]){
		res.push_back(i);
		for(auto &j : adj[i]){
			if(used[i] or sz(adj[j]) == 1)
				continue;
			res.push_back(j);
			res.push_back(i);
		}
	}
	cout << "YES\n" << (sz(res) << 1) << "\n";
	for(auto &i : res) cout << i << " ";
	reverse(all(res));
	for(auto &i : res) cout << i << " ";
}

signed main(int argc, char *argv[]){
	iostream::sync_with_stdio(0);
	int T = 1; 
	while(T--) rmain();
	return 0;
}

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