Submission #529316

#	Time	Username	Problem	Language	Result	Execution time	Memory
529316		Alex_tz307	Network (BOI15_net)	C++17	0 / 100	1 ms	316 KiB

net

#include <bits/stdc++.h>

using namespace std;

void testCase() {
  int n;
  cin >> n;
  vector<int> d(n + 1);
  for (int i = 1; i < n; ++i) {
    int u, v;
    cin >> u >> v;
    d[u] += 1;
    d[v] += 1;
  }
  int node = -1;
  vector<int> v;
  for (int i = 1; i <= n; ++i) {
    if (d[i] == 1) {
      v.emplace_back(i);
    } else {
      node = i;
    }
  }
  if ((int)v.size() % 2 == 1) {
    v.emplace_back(node);
  }
  cout << v.size() / 2 << '\n';
  for (int i = 0; i < (int)v.size(); i += 2) {
    cout << v[i] << ' ' << v[i + 1] << '\n';
  }
}

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  int tests = 1;
  for (int tc = 0; tc < tests; ++tc) {
    testCase();
  }
  return 0;
}

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