Submission #751028

#	Time	Username	Problem	Language	Result	Execution time	Memory
751028		ljuba	Network (BOI15_net)	C++17	0 / 100	1 ms	212 KiB

net

#include <bits/stdc++.h>

using namespace std;

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);

    int n;
    cin >> n;

    vector<int> deg(n);

    for(int i = 1; i < n; ++i) {
        int u, v;
        cin >> u >> v;
        --u, --v;

        ++deg[u], ++deg[v];
    }

    vector<int> lisce;
    for(int i = 0; i < n; ++i) {
        if(deg[i] == 1) lisce.push_back(i);
    }

    assert(lisce.size() != 1);

    cout << (lisce.size() + 1) / 2 << '\n';

    for(int i = 0; i < lisce.size(); i += 2) {
        int x = lisce[i];
        int y = lisce[(i + 1) % lisce.size()];
        cout << x + 1 << " " << y + 1 << '\n';
    }
}

Compilation message (stderr)

net.cpp: In function 'int main()':
net.cpp:31:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   31 |     for(int i = 0; i < lisce.size(); i += 2) {
      |                    ~~^~~~~~~~~~~~~~

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