Submission #826008

#	Time	Username	Problem	Language	Result	Execution time	Memory
826008		Darren0724	Network (BOI15_net)	C++17	100 / 100	829 ms	47572 KiB

net

#include<bits/stdc++.h>
using namespace std;
vector<int> ans;
vector<vector<int>> adj;
void dfs(int k,int pa){
    if(adj[k].size()==1){
        ans.push_back(k);
    }
    for(int j:adj[k]){
        if(j==pa){
            continue;
        }
        dfs(j,k);
    }
}
int main(){
    int n;cin>>n;
    adj.resize(n);
    for(int i=1;i<n;i++){
        int a,b;cin>>a>>b;a--;b--;
        adj[a].push_back(b);
        adj[b].push_back(a);
    }
    dfs(0,0);
    int m=ans.size();
    for(int &j:ans){
        j++;
    }
    cout<<(m+1)/2<<endl;
    for(int i=0;i<m/2;i++){
        cout<<ans[i]<<' '<<ans[i+m/2]<<endl;
    }
    if(m&1){
        cout<<ans[0]<<' '<<ans[m-1]<<endl;
    }
}

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