Submission #993879

#	Time	Username	Problem	Language	Result	Execution time	Memory
993879		Nexus	Network (BOI15_net)	C++17	0 / 100	1 ms	604 KiB

net

#include <bits/stdc++.h>
#define ll long long

using namespace std;

const ll N=2e5+9,M=2e18+9,mod=1e9+7;

ll n,x,y,z;
map<ll,ll>m;
vector<ll>v;

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);

    cin>>n;
    while(--n)
    {
        cin>>x>>y;
        ++m[x],++m[y];
    }
    for(auto i:m)
    {
        if(i.second==1)v.push_back(i.first);
    }
    n=v.size();
    cout<<n/2+n%2<<'\n';
    for(ll i=1;i<n;i+=2)cout<<v[i]<<' '<<v[i-1]<<'\n';
    if(n&1)cout<<v[n-1]<<' '<<v[0];
}

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