Submission #672870

#	Time	Username	Problem	Language	Result	Execution time	Memory
672870		iosif_andrei_	Network (BOI15_net)	C++14	0 / 100	8 ms	12044 KiB

net

#include <bits/stdc++.h> 
using namespace std;

int n;
vector <int> g[500001];
vector <int> v;

int main() {
    
    cin >> n;

    for (int i = 1; i < n; i++)
    {
        int x, y;
        cin >> x >> y;
        g[x].push_back(y);
        g[y].push_back(x);
    }

    for (int i = 1; i <= n; i++)
        if (g[i].size() == 1)
            v.push_back(i);

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

    for (int i = 0; i < v.size() - 1; i += 2)
        cout << v[i] << ' ' << v[i + 1] << '\n';

    if (v.size() % 2)
        if (g[v.back()].back() == 1)
            cout << v.back() << ' ' << 2;
        else
            cout << v.back() << ' ' << 1;

    return 0;
}

Compilation message (stderr)

net.cpp: In function 'int main()':
net.cpp:26:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   26 |     for (int i = 0; i < v.size() - 1; i += 2)
      |                     ~~^~~~~~~~~~~~~~
net.cpp:29:8: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
   29 |     if (v.size() % 2)
      |        ^

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