Submission #528154

#	Time	Username	Problem	Language	Result	Execution time	Memory
528154		jesus_coconut	Newspapers (CEOI21_newspapers)	C++17	8 / 100	2 ms	332 KiB

newspapers

#include <bits/stdc++.h>

using namespace std;

int n, m;
vector<vector<int>> adj;

void load() {
  cin >> n >> m;
  adj.resize(n);
  for (int i = 0; i < m; ++i) {
	int a, b;
	cin >> a >> b;
	--a; --b;
	adj[a].push_back(b);
	adj[b].push_back(a);
  }
}

int const N = 1024;

bitset<N> bio;



void solve2() {
  if (n <= 3) {
	cout << "YES\n";
	cout << "2\n2 2\n";
	return;
  }
  cout << "YES\n";
  cout << 2 * n - 4 << '\n';
  for (int i = 2; i < n; ++i) {
	cout << i << ' ';
  }
  for (int i = n - 1; i > 1; --i) {
	cout << i << ' ';
  }
  cout << '\n';
}

bool isLine() {
  for (int i = 0; i < n - 1; ++i) {
	bool good = false;
	for (auto u : adj[i]) {
	  good |= (u == i + 1);
	}
	if (!good) return false;
  }
  return true;
}

int isStar() {
  for (int i = 0; i < n; ++i) {
	if (size(adj[i]) == n - 1) {
	  return i + 1;
	}
  }
  return -1;
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  load();
  if (m >= n) {
	cout << "NO\n";
	return 0;
  }
  if (n == 1) {
	cout << "YES\n";
	cout << "1\n1\n";
	return 0;
  }
  if (isLine()) {
	solve2();
	return 0;
  }
  int c = isStar();
  if (c > -1) {
	cout << "YES\n";
	cout << 2 << '\n';
	cout << c << ' ' << c << '\n';
	return 0;
  }
  cout << "NO\n";

  return 0;
}

Compilation message (stderr)

newspapers.cpp: In function 'int isStar()':
newspapers.cpp:56:19: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   56 |  if (size(adj[i]) == n - 1) {
      |      ~~~~~~~~~~~~~^~~~~~~~

• Subtask 1: 0 / 12
• Subtask 2: 8 / 8
• Subtask 3: 0 / 80