Submission #1213411

#	Time	Username	Problem	Language	Result	Execution time	Memory
1213411		minhpk	Network (BOI15_net)	C++20	0 / 100	15 ms	23880 KiB

net

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

int n;
vector<int> adj[1000005];
vector<int> leaves;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    cin >> n;

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

    for (int i = 1; i <= n; i++) {
        if (adj[i].size() == 1) {
            leaves.push_back(i);
        }
    }

    int k = (leaves.size() + 1) / 2;
    cout << k << '\n';

    for (int i = 0; i < leaves.size() / 2; i++) {
        cout << leaves[i] << " " << leaves[i + (leaves.size() + 1) / 2] << '\n';
    }

    if (leaves.size() % 2 == 1) {
        cout << leaves[(leaves.size() - 1) / 2] << " " << leaves.back() << '\n';
    }

    return 0;
}

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