제출 #1036989

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1036989		___	Network (BOI15_net)	C++17	0 / 100	0 ms	416 KiB

net

#include <bits/stdc++.h>
#define int long long int
#define ff first
#define ss second
#define FT ios_base::sync_with_stdio(false);cin.tie(0);
using namespace std;
const int maxn = 5e5 + 10;
int degree[maxn];
vector <int> leaf;
signed main()
{
	FT;
	int n;
	cin >> n;
	for (int i = 1 ; i < n ; i++)
	{
		int a , b;
		cin >> a >> b;
		degree[a]++;
		degree[b]++;
	}
	for (int i = 1 ; i <= n ; i++)
	{
		if (degree[i] == 1)
		{
			leaf.push_back(i);
		}
	}
	int k = leaf.size();
	cout << (k + 1) / 2 << endl;
	for (int i = 0 ; i < k - 1 ; i += 2)
	{
		cout << leaf[i] << " " << leaf[i + 1] << endl;
	}
	if (k % 2)
	{
		cout << leaf[0] << " " << leaf[k - 1];
	}
	return 0;	
}

• Subtask 1: 0 / 18
• Subtask 2: 0 / 45
• Subtask 3: 0 / 37