oj.uz

Submission #605110

# Submission time Handle Problem Language Result Execution time Memory
605110 2022-07-25T13:06:02 Z tamthegod Network (BOI15_net) C++14
0 / 100
 16 ms 23820 KB 
#include<bits/stdc++.h>

#define int long long
#define pb push_back
#define fi first
#define se second
using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int maxN = 1e6 + 5;
const int mod = 1e9 + 7;
const ll oo = 1e18;
int n;
vector<int> adj[maxN];
int depth[maxN];
void ReadInput()
{
    cin >> n;
    for(int i=1; i<n; i++)
    {
        int u, v;
        cin >> u >> v;
        adj[u].pb(v);
        adj[v].pb(u);
    }
}
void dfs(int u, int par)
{
    for(int v : adj[u])
    {
        if(v == par) continue;
        depth[v] = depth[u] + 1;
        dfs(v, u);
    }
}
void Solve()
{
    dfs(1, 0);
    vector<int> leaf;
    for(int i=1; i<=n; i++)
    {
        if(adj[i].size() == 1) leaf.pb(i);
    }
    int l = 0, step = leaf.size() / 2;
    if(leaf.size() % 2 == 0)
    {
        cout << leaf.size() / 2 << '\n';
        while(l + step < leaf.size())
        {
            cout << leaf[l] << " " << leaf[l + step] << '\n';
            l++;
        }
        return;
    }
    leaf.pb(leaf[0]);
    step++;
    cout << leaf.size() / 2 << '\n';
    while(l + step < leaf.size())
    {
        cout << leaf[l] << " " << leaf[l + step] << '\n';
        l++;
    }
}
int32_t main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    ReadInput();
    Solve();
}

Compilation message

net.cpp: In function 'void Solve()':
net.cpp:50:24: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   50 |         while(l + step < leaf.size())
      |               ~~~~~~~~~^~~~~~~~~~~~~
net.cpp:60:20: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   60 |     while(l + step < leaf.size())
      |           ~~~~~~~~~^~~~~~~~~~~~~

Subtask #1
0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 23712 KB Output is correct
2 Correct 12 ms 23748 KB Output is correct
3 Correct 15 ms 23764 KB Output is correct
4 Correct 15 ms 23808 KB Output is correct
5 Correct 15 ms 23732 KB Output is correct
6 Correct 16 ms 23820 KB Output is correct
7 Correct 14 ms 23764 KB Output is correct
8 Correct 14 ms 23764 KB Output is correct
9 Correct 13 ms 23692 KB Output is correct
10 Correct 16 ms 23808 KB Output is correct
11 Correct 15 ms 23696 KB Output is correct
12 Incorrect 13 ms 23764 KB Breaking single line is causing network to disconnect.
13 Halted 0 ms 0 KB -

Subtask #2
0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 23712 KB Output is correct
2 Correct 12 ms 23748 KB Output is correct
3 Correct 15 ms 23764 KB Output is correct
4 Correct 15 ms 23808 KB Output is correct
5 Correct 15 ms 23732 KB Output is correct
6 Correct 16 ms 23820 KB Output is correct
7 Correct 14 ms 23764 KB Output is correct
8 Correct 14 ms 23764 KB Output is correct
9 Correct 13 ms 23692 KB Output is correct
10 Correct 16 ms 23808 KB Output is correct
11 Correct 15 ms 23696 KB Output is correct
12 Incorrect 13 ms 23764 KB Breaking single line is causing network to disconnect.
13 Halted 0 ms 0 KB -

Subtask #3
0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 23712 KB Output is correct
2 Correct 12 ms 23748 KB Output is correct
3 Correct 15 ms 23764 KB Output is correct
4 Correct 15 ms 23808 KB Output is correct
5 Correct 15 ms 23732 KB Output is correct
6 Correct 16 ms 23820 KB Output is correct
7 Correct 14 ms 23764 KB Output is correct
8 Correct 14 ms 23764 KB Output is correct
9 Correct 13 ms 23692 KB Output is correct
10 Correct 16 ms 23808 KB Output is correct
11 Correct 15 ms 23696 KB Output is correct
12 Incorrect 13 ms 23764 KB Breaking single line is causing network to disconnect.
13 Halted 0 ms 0 KB -