Submission #476064

#	Time	Username	Problem	Language	Result	Execution time	Memory
476064		Blobo2_Blobo2	Network (BOI15_net)	C++14	0 / 100	8 ms	12064 KiB

net

/*
Editor: Abdelrahman Hossam
Nickname: Blobo2_Blobo2
IOI next year isA :)
*/
/*#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math,O3")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,sse4.2,popcnt,abm,mmx,avx2,tune=native")
#pragma GCC optimize("-ffast-math")
#pragma GCC optimize("-funroll-loops")
#pragma GCC optimize("-funroll-all-loops,-fpeel-loops,-funswitch-loops")*/

#include<bits/stdc++.h>
using namespace std;
//#define int long long
#define endl "\n"
#define all(v)  v.begin(),v.end()
#define gen(arr,n,nxt)  generate(arr,arr+n,nxt)
#define Blobo2_el_7akim_elly_3ayz_yro7_IOI_w_3ayz_yakol_jilaty ios_base::sync_with_stdio(false);cin.tie(0);
#define EPS 0.00000001

const int mo=1e9+7,INF=1e18;
int nxt(){int x;cin>>x;return x;}
vector<int>adj[500001];
bool vis[500001];
vector<int>leaves;
void dfs(int u=0){
    vis[u]=1;
    if(adj[u].size()==1)
        leaves.push_back(u);
    for(auto v:adj[u]){
        if(!vis[v])
            dfs(v);
    }
}
signed main(){
    Blobo2_el_7akim_elly_3ayz_yro7_IOI_w_3ayz_yakol_jilaty
    int n=nxt();
    for(int i=0;i<n-1;i++){
        int x=nxt()-1,y=nxt()-1;
        adj[x].push_back(y);
        adj[y].push_back(x);
    }
    dfs();
    int leaf = leaves.size();
    cout<<(leaf+1)/2<<endl;
    for(int i=0;i<leaves.size();i+=2)
        cout<<leaves[i]+1<<' '<<leaves[(i+1)%leaf]+1<<endl;
    return 0;
}

Compilation message (stderr)

net.cpp:21:24: warning: overflow in conversion from 'double' to 'int' changes value from '1.0e+18' to '2147483647' [-Woverflow]
   21 | const int mo=1e9+7,INF=1e18;
      |                        ^~~~
net.cpp: In function 'int main()':
net.cpp:46:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   46 |     for(int i=0;i<leaves.size();i+=2)
      |                 ~^~~~~~~~~~~~~~

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