Submission #1189058

#	Time	Username	Problem	Language	Result	Execution time	Memory
1189058		pxsit	Network (BOI15_net)	C++20	0 / 100	0 ms	328 KiB

net

#include <bits/extc++.h>
using namespace std;
typedef long long ll;
int main(){
    ios::sync_with_stdio(false);
    cin.tie(NULL);
    int n;
    cin>>n;
    vector<int> deg(n+1);
    for(int i=0;i<n-1;i++){
        int a,b;
        cin>>a>>b;
        deg[a]++;deg[b]++;
    }
    vector<int> leaves;
    for(int i=1;i<=n;i++){
        if(deg[i]==1) leaves.emplace_back(i);
    }
    int l=leaves.size(), m=l/2;
    vector<pair<int,int>> ans;
    for(int i=0;i<m;i++){
        ans.emplace_back(leaves[i],leaves[i+m]);
    }
    if(l%2){
        ans.emplace_back(leaves[l-1],leaves[m]);
    }
    cout<<ans.size()<<"\n";
    for(auto &p:ans){
        cout<<p.first<<" "<<p.second<<"\n";
    }
    return 0;
}

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