Submission #730624

#	Time	Username	Problem	Language	Result	Execution time	Memory
730624		penguin133	Network (BOI15_net)	C++17	0 / 100	1 ms	340 KiB

net

#include <bits/stdc++.h>
using namespace std;

#define int long long
#define pi pair<int, int>
#define pii pair<int, pi>
#define fi first
#define se second
#ifdef _WIN32
#define getchar_unlocked _getchar_nolock
#endif
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

int deg[500005];

void solve(){
	int n; cin >> n;
	for(int i=1;i<n;i++){
		int a, b; cin >> a >> b;
		deg[a]++; deg[b]++;
	}
	vector <int> adj;
	for(int i=1;i<=n;i++)if(deg[i] == 1)adj.push_back(i);
	cout << ((int)adj.size() + 1) / 2 << '\n';
	for(int i=0;i<(int)adj.size();i+=2){
		if(i == (int)adj.size() - 1)cout << adj[i] << ' ' << 1 << '\n';
		else cout << adj[i] << ' ' << adj[i+1] << '\n';
	}
}

main(){
	ios::sync_with_stdio(0);cin.tie(0);
	int tc = 1;
	//cin >> tc;
	for(int tc1=1;tc1<=tc;tc1++){
		// cout << "Case #" << tc1 << ": ";
		solve();
	}
}

Compilation message (stderr)

net.cpp:31:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   31 | main(){
      | ^~~~

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