Submission #717227

#	Time	Username	Problem	Language	Result	Execution time	Memory
717227		hollwo_pelw	Newspapers (CEOI21_newspapers)	C++17	100 / 100	2 ms	468 KiB

newspapers

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

using namespace std;
// using namespace __gnu_cxx;
// using namespace __gnu_pbds;

void Hollwo_Pelw();

signed main(){
#ifndef hollwo_pelw_local
	if (fopen(".inp", "r"))
		assert(freopen(".inp", "r", stdin)), assert(freopen(".out", "w", stdout));
#else
	using namespace chrono;
	auto start = steady_clock::now();
#endif
	cin.tie(0), cout.tie(0) -> sync_with_stdio(0);
	int testcases = 1;
	// cin >> testcases;
	for (int test = 1; test <= testcases; test++){
		// cout << "Case #" << test << ": ";
		Hollwo_Pelw();
	}
#ifdef hollwo_pelw_local
	auto end = steady_clock::now();
	cout << "\nExecution time : " << duration_cast<milliseconds> (end - start).count() << "[ms]" << endl;
#endif
}

const int N = 1005;

int n, m, S, T, hS[N], hT[N], path[N];
vector<int> adj[N], res;

void dfs(int u, int p, int *h) {
	h[u] = p ? h[p] + 1 : 0;
	for (int v : adj[u]) if (v != p)
		dfs(v, u, h);
}

void Hollwo_Pelw(){
	cin >> n >> m;
	if (m >= n) return cout << "NO\n", (void) 0;
	for (int i = 1, u, v; i < n; i++) {
		cin >> u >> v;
		adj[u].push_back(v);
		adj[v].push_back(u);
	}

	if (n == 1) return cout << "YES\n1\n1\n", (void) 0;
	if (n == 2) return cout << "YES\n2\n1 1\n", (void) 0;
	dfs(1, 0, hS);
	S = max_element(hS + 1, hS + n + 1) - hS, dfs(S, 0, hS);
	T = max_element(hS + 1, hS + n + 1) - hS, dfs(T, 0, hT);

	const int LEN = hS[T];

	// cout << LEN << '\n';
	// cout << S << ' ' << T << '\n';

	for (int i = 1; i <= n; i++) {
		if (hS[i] + hT[i] > LEN + 4) // can not reach ?
			return cout << "NO\n", (void) 0;
		if (hS[i] + hT[i] == LEN)
			path[hS[i]] = i;
	}

	// for (int i = 1; i <= n; i++)
	// 	cout << hS[i] + hT[i] << " \n"[i == n];

	for (int i = 1; i <= LEN - 1; i++) {
		int u = path[i];
		res.push_back(u);
		for (int v : adj[u])
			if (hS[v] + hT[v] > LEN && (int) adj[v].size() > 1)
				res.push_back(v), res.push_back(u);
	}

	for (int i = LEN - 1; i >= 1; i--) {
		int u = path[i];
		res.push_back(u);
		for (int v : adj[u])
			if (hS[v] + hT[v] > LEN && (int) adj[v].size() > 1)
				res.push_back(v), res.push_back(u);
	}

	cout << "YES\n";
	cout << res.size() << '\n';
	for (int x : res)
		cout << x << ' ';
	cout << '\n';
}

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