Submission #1140799

#	Time	Username	Problem	Language	Result	Execution time	Memory
1140799		huoi	Network (BOI15_net)	C++17	0 / 100	0 ms	328 KiB

net

#include <bits/stdc++.h>

using namespace std;

#define int long long
#define INF 9e18

void solve() {
    int n;
    cin >> n;

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

    vector<int> leaves;
    for (int u = 0; u < n; u++) {
        if (adj[u].size() == 1) {
            leaves.push_back(u + 1);
        }
    }

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

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    solve();
    return 0;
}

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