Submission #41211

#	Time	Username	Problem	Language	Result	Execution time	Memory
41211		wzy	Network (BOI15_net)	C++14	0 / 100	12 ms	12460 KiB

net

#include <bits/stdc++.h>
using namespace std;
int n;
vector<int> adj[500005];

int main(){
	cin>>n;
	for(int i= 0 ; i < n - 1 ; i++){
		int x ,y;
		cin>>x>>y;
		x-- , y--;
		adj[x].push_back(y);
		adj[y].push_back(x);
	}
	vector<int> tocreate;
	int lastv = -1;
	for(int i = 0 ; i < n; i++){
		if(adj[i].size() == 1) tocreate.push_back(i);
	}
	vector<pair<int,int> > edges;
	while(!tocreate.empty()){
		if(tocreate.size() == 1){
			edges.push_back(pair<int,int>(lastv , tocreate.back()));
			break;
		}
		else{
			int u = tocreate.back();
			tocreate.pop_back();
			int v = tocreate.back();
			tocreate.pop_back();
			lastv = v;
			edges.push_back(pair<int,int>(lastv,u));
		}
	}
	cout<<edges.size()<<endl;
	for(int j = 0 ; j < edges.size() ; j++){
		pair<int,int> v = edges[j];
		cout<<v.first + 1 <<" " << v.second + 1 << endl;
	}

}

Compilation message (stderr)

net.cpp: In function 'int main()':
net.cpp:36:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int j = 0 ; j < edges.size() ; j++){
                    ^

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