Submission #959600

#	Time	Username	Problem	Language	Result	Execution time	Memory
959600		Blagoj	Network (BOI15_net)	C++17	0 / 100	1 ms	468 KiB

net

#include <bits/stdc++.h>

using namespace std;

#define endl '\n'
#define ll long long
#define all(x) (x).begin(), (x).end()

const int mxn = 5e5 + 10;

int deg[mxn];

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int n;
    cin >> n;
    for (int i = 0; i < n - 1; i++) {
        int f, t;
        cin >> f >> t;
        deg[f]++;
        deg[t]++;
    }
    vector<int> leafs;
    for (int i = 1; i <= n; i++) if (deg[i] == 1) leafs.push_back(i);
    int sz = leafs.size();
    vector<pair<int, int>> v;
    for (int i = 0; i < sz / 2; i++) v.push_back({leafs[i], leafs[i + sz / 2]});
    if (sz % 2 != 0) v.push_back({leafs[0], leafs.back()});
    cout << v.size() << endl;
    for (auto x : v) cout << x.first << " " << x.second << endl;
}

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