Submission #32315

#	Time	Username	Problem	Language	Result	Execution time	Memory
32315		dqhungdl	Network (BOI15_net)	C++14	18 / 100	3 ms	14380 KiB

net

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

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

void DFS(int u)
{
    Free[u]=true;
    if(g[u].size()==1)
        V.push_back(u);
    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);
    }
    DFS(1);
    int res=(V.size()+1)/2;
    cout<<res<<"\n";
    for(int i=0;i<res;i++)
        if(i+V.size()/2<V.size())
            cout<<V[i]<<' '<<V[i+V.size()/2]<<"\n";
}

Compilation message (stderr)

net.cpp: In function 'void DFS(int)':
net.cpp:13:18: 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