Submission #32313

#	Time	Username	Problem	Language	Result	Execution time	Memory
32313		dqhungdl	Network (BOI15_net)	C++14	18 / 100	9 ms	14380 KiB

net

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

int n;
bool Free[500005];
vector<int> V,g[500005];

inline void DFS(int u)
{
    Free[u]=true;
    if(g[u].size()==1)
    {
        V.push_back(u);
        return;
    }
    for(int i=0;i<g[u].size();i++)
        if(Free[g[u][i]]==false)
            DFS(g[u][i]);
}

int main()
{
    ios_base::sync_with_stdio(false);
    //freopen("NET.INP","r",stdin);
    cin>>n;
    int u,v;
    for(int i=1;i<n;i++)
    {
        cin>>u>>v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    for(int i=1;i<=n;i++)
        if(g[i].size()>=2)
        {
            DFS(i);
            break;
        }
    int tmp=V.size();
    cout<<(tmp+1)/2<<"\n";
    for(int i=0;i<=(tmp-1)/2;i++)
        cout<<V[i]<<' '<<V[i+tmp/2]<<"\n";
}

Compilation message (stderr)

net.cpp: In function 'void DFS(int)':
net.cpp:16:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<g[u].size();i++)
                  ^

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