Submission #876008

#	Time	Username	Problem	Language	Result	Execution time	Memory
876008		vjudge1	Network (BOI15_net)	C++17	0 / 100	1 ms	348 KiB

net

#include <bits/stdc++.h>
using namespace std;
int main(){
	int n;
	cin>>n;
	vector<int> links[n+1];
	for(int i=0; i<n-1; i++){
		int a,b;
		cin>>a>>b;
		links[a].push_back(b);
		links[b].push_back(a);
	}
	int last=0;
	int total=0;
	vector<pair<int,int>> ans;
	for(int i=1; i<=n; i++){
		if(links[i].size()==1){
			if(last==0){
				last=i;
			}
			else{
				total++;
				ans.push_back({last,i});
				last=0;
			}
		}
	}
	if(last!=0){
		total++;
		if(last==1){
			ans.push_back({last,2});
		}
		else{
			ans.push_back({last,1});
		}
	}
	cout<<total<<endl;
	for(int i=0; i<ans.size(); i++){
		cout<<ans[i].first<<' '<<ans[i].second<<endl;
	}
}

Compilation message (stderr)

net.cpp: In function 'int main()':
net.cpp:38:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   38 |  for(int i=0; i<ans.size(); i++){
      |               ~^~~~~~~~~~~

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