Submission #765395

#	Time	Username	Problem	Language	Result	Execution time	Memory
765395		vjudge1	Network (BOI15_net)	C++17	100 / 100	362 ms	52380 KiB

net

/**
  * Author: Amirrrr
  * Created: 24.06.2023
  * Why am I so stupid? :c
  * Slishkom slab
**/

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

#define ll long long
#define pb push_back
#define all(x) x.begin(), x.end()
#define FF first
#define SS second
#define ent "\n"
#define int long long

const int N = 5e5 + 13;
const int MOD = 1e9 + 7;
const int INF = 1e18;
const int maxn = 1e6 + 12;

int n,x,y,used[N];
vector<int>g[N],ord;

void dfs(int v){
    used[v]=1;
    if(g[v].size()==1){
        ord.pb(v);
    }
    for(auto to:g[v]){
        if(!used[to]){
            dfs(to);
        }
    }
}

void gogo (){
    cin>>n;
    for(int i=1;i<n;i++){
        int x,y;cin>>x>>y;
        g[x].pb(y),g[y].pb(x);
    }
    dfs(1);
    cout<<(ord.size()+1)/2<<ent;
    for(int i=0;i<ord.size()/2;i++){
        cout<<ord[i]<<' '<<ord[i+ord.size()/2]<<ent;
    }
    if(ord.size()%2){
        cout<<ord.back()<<' '<<ord[0]<<ent;
    }
}

signed main (/*Amir Mirmanov*/){
    ios_base::sync_with_stdio(0),cin.tie(0);
    int Q=1,test=1;
    //freopen("rain.in","r",stdin);
	//freopen("rain.out","w",stdout);
    //cin>>Q;
    while (Q --){
        gogo();
    }
    return 0;
}

Compilation message (stderr)

net.cpp: In function 'void gogo()':
net.cpp:47:18: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   47 |     for(int i=0;i<ord.size()/2;i++){
      |                 ~^~~~~~~~~~~~~
net.cpp: In function 'int main()':
net.cpp:57:13: warning: unused variable 'test' [-Wunused-variable]
   57 |     int Q=1,test=1;
      |             ^~~~

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