Submission #1207417

#	Time	Username	Problem	Language	Result	Execution time	Memory
1207417		rhm_gan	Network (BOI15_net)	C++20	0 / 100	5 ms	12104 KiB

net

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

#ifdef LOCAL
#include "debug.h"
#else
#define dbg(...) 42
#endif

#define int long long

const int N = 5e5 + 1;
vector<int> adj[N];

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    cin >> n;

    for (int i = 1; i < n; i++) {
    	int a, b;
    	cin >> a >> b;
    	adj[a].push_back(b);
    	adj[b].push_back(a);
    }

    vector<int> v;
    int u;
    for (int i = 1; i <= n; i++) {
    	if (adj[i].size() == 1) {
    		v.push_back(i);
    	}
    	else {
    		u = i;
    	}
    }

   	int m = v.size();
   	cout << (m + 1) / 2 << '\n';
   	for (int i = 0; i < m - 1; i += 2) {
   		cout << v[i] << ' ' << v[i + 1] << '\n';
   	}
   	if (m & 1) {
   		cout << v.back() << ' ' << u << '\n'; 
   	}

    return 0;
}

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