Submission #584967

#	Time	Username	Problem	Language	Result	Execution time	Memory
584967		Newtech66	Network (BOI15_net)	C++17	0 / 100	9 ms	14036 KiB

net

#include<bits/stdc++.h>
using namespace std;
using lol=long long int;
#define endl "\n"
const lol mod1=1e9+7,mod2=998244353,mod3=1000000000000000003;
const lol inf=1e18+8;
const double eps=1e-12;
const double PI=acos(-1.0);
const int N=5e5+5;
#include <ext/pb_ds/assoc_container.hpp> // Common file
#include <ext/pb_ds/tree_policy.hpp> // Including tree_order_statistics_node_update
using namespace __gnu_pbds;
typedef tree<pair<int,int>,null_type,less<pair<int,int> >,rb_tree_tag,tree_order_statistics_node_update> ordered_set;
//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
vector<vector<int>> g(N);
vector<int> deg(N,0);
vector<int> leaves;
vector<pair<int,int>> edges;

int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int _=1;
//cin>>_;
while(_--)
{
    int n;
    cin>>n;
    for(int i=0;i<n-1;i++)
    {
        int u,v;
        cin>>u>>v;
        deg[u]++,deg[v]++;
    }
    for(int i=1;i<=n;i++)
    {
        if(deg[i]==1)   leaves.push_back(i);
    }
    for(int i=0;i<(int)leaves.size()-1;i+=2)
    {
        edges.push_back({leaves[i],leaves[i+1]});
    }
    if((int)leaves.size()%2==1) edges.push_back({leaves[0],leaves.back()});
    cout<<edges.size()<<endl;
    for(auto [a,b]:edges)   cout<<a<<" "<<b<<endl;
}
return 0;
}

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