Submission #394681

#	Time	Username	Problem	Language	Result	Execution time	Memory
394681		MahdiBahramian	Network (BOI15_net)	C++17	100 / 100	761 ms	45216 KiB

net

#include<bits/stdc++.h>
#define pb push_back
using namespace std;
const int Max = 5e5 + 10;

vector<int> N[Max]; 
vector<int> L;
void DFS(int v , int p = 0)
{
	if(N[v].size() == 1) L.pb(v);
	for(int u : N[v]) if(u != p) DFS(u , v);
}

int main()
{
	int n; cin >> n;
	for(int i = 1 , a , b ; i < n ; i++) cin >> a >> b , N[a].pb(b) , N[b].pb(a);
	DFS(1);
	cout << (L.size() + 1) / 2 << '\n';
	for(int i = 0 , j = L.size() / 2 ; j < L.size() ; i++ , j++) cout << L[i] << ' ' << L[j] << '\n';
}

Compilation message (stderr)

net.cpp: In function 'int main()':
net.cpp:20:39: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   20 |  for(int i = 0 , j = L.size() / 2 ; j < L.size() ; i++ , j++) cout << L[i] << ' ' << L[j] << '\n';
      |                                     ~~^~~~~~~~~~

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