Submission #402848

#	Time	Username	Problem	Language	Result	Execution time	Memory
402848		bigDuck	Network (BOI15_net)	C++14	0 / 100	1 ms	384 KiB

net

#include<bits/stdc++.h>
using namespace std;
#define INIT  ios_base :: sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define mp make_pair
#define pb push_back
#define ft first
#define sc second
#define ll long long
#define pii pair<int, int>
#define count_bits __builtin_popcount
#define int ll

int t, n, m, k, a[300010], q, l, r;
int dg[500010];

int32_t main(){
INIT
cin>>n;
for(int i=1; i<n; i++){
    int u, v;
    cin>>u>>v;
    dg[u]++; dg[v]++;
}
vector<int> v;
for(int i=1; i<=n; i++){
    if(dg[i]==1){
        v.pb(i);
    }
}
vector<pii> res;
int lt=0;
while(v.size()>0){
    if(v.size()==1){
        res.pb({lt, v.back()});
        v.pop_back();
    }
    else{
        lt=v.back();
        v.pop_back();
        res.pb({lt, v.back()});
        v.pop_back();
    }
}
cout<<res.size()<<"\n";
for(auto pr:res){
    cout<<pr.ft<<" "<<pr.sc<<"\n";
}

return 0;
}

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