Submission #1033239

#	Time	Username	Problem	Language	Result	Execution time	Memory
1033239		aufan	Network (BOI15_net)	C++17	0 / 100	1 ms	348 KiB

net

#include <bits/stdc++.h>
#define int long long
#define fi first
#define se second

using namespace std;

int32_t main()
{
        ios_base::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] += 1;
                deg[b] += 1;
        }

        vector<int> leafs; // lol
        for (int i = 1; i <= n; i++) {
                if (deg[i] == 1) {
                        leafs.push_back(i);
                }
        }

        if ((int)leafs.size() % 2 == 1) {
                for (int i = 1; i <= n; i++) {
                        if (deg[i] > 1) {
                                leafs.push_back(i);
                                break;
                        }
                }
        }

        vector<pair<int, int>> ans;
        for (int i = 0; i < (int)leafs.size(); i += 2) {
                ans.push_back({leafs[i], leafs[i + 1]});
        }

        cout << (int)ans.size() << '\n';
        for (auto [a, b] : ans) cout << a << " " << b << '\n';
        
        return 0;
}

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