Submission #151239

#	Time	Username	Problem	Language	Result	Execution time	Memory
151239		cfalas	Network (BOI15_net)	C++14	100 / 100	1455 ms	53260 KiB

net

#include<bits/stdc++.h>
using namespace std;
vector<vector<int> > adj;
vector<int> ans;

void dfs(int s, int p=-1){
	if(adj[s].size()==1){
		ans.push_back(s);
	}
	for(auto v : adj[s] ){
		if(v!=p) dfs(v, s);
	}
}
 
int main(){
	int n;
	adj.assign(1000000, vector<int>());
	cin>>n;
	for(int i=0;i<n-1;i++){
		int b, c;
		cin>>b>>c;
		adj[b].push_back(c);
		adj[c].push_back(b);
	}
	dfs(1);
	cout<<(ans.size()+1)/2<<endl;
	for(int i=0;i<(ans.size()+1)/2;i++){
		cout<<ans[i]<<" "<<ans[(i+(ans.size()+1)/2)%ans.size()]<<endl;
	}
 
}

Compilation message (stderr)

net.cpp: In function 'int main()':
net.cpp:27:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<(ans.size()+1)/2;i++){
              ~^~~~~~~~~~~~~~~~~

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