oj.uz

Submission #656276

# Submission time Handle Problem Language Result Execution time Memory
656276 2022-11-06T17:02:03 Z ilia_rr Network (BOI15_net) C++17
0 / 100
 68 ms 112188 KB 
// بِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيمِ
// Written by Ilia Rahbar

// #pragma GCC optimize ("O3,no-stack-protector,unroll-loops,fast-math")
// #pragma GCC target ("abm,bmi,bmi2,tbm,avx2")

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

#define int int64_t
#define ai(x) array <int, x>
#define F first 
#define S second

const int MOD = 1e9 + 7, N = 1e6 + 100;

int c, n, u[N], v[N], d[N], stc, l, r, co[N], mv = 1e9, fv[N];

vector <int> g[N], st[N], ans[2];

void dfs(int inx)
{
    if (g[inx].size() == 1)
        st[stc].push_back(inx);

    for (auto i : g[inx])
    {
        if (!d[i])
        {
            d[i] = 1;

            dfs(i);
        }
    }
}

void dfs0(int inx, int par)
{
    d[inx] = d[par] + 1;

    co[inx] = (g[inx].size() == 1);

    for (auto i : g[inx])
    {
        if (d[i])
            continue;
        
        dfs0(i, inx);

        co[inx] += co[i];
    }
}       

int32_t main()
{
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    
    cin >> n;

    for (int i = 1; i < n; i++)
        cin >> u[i] >> v[i], g[u[i]].push_back(v[i]), g[v[i]].push_back(u[i]);
    
    dfs0(1, 0);

    for (int i = 1; i <= n; i++)
    {
        if (g[i].size() > g[c].size())
            c = i;
    }

    for (int i = 1; i < n; i++)
    {
        if (d[u[i]] > d[v[i]])
            swap(u[i], v[i]);

        if (abs(co[v[i]] - (co[1] - co[v[i]])) <= mv)
        {
            mv = abs(co[v[i]] - (co[1] - co[v[i]]));
            
            if (co[v[i]] < (co[1] - co[v[i]]) && g[u[i]].size() > 1)
                c = u[i];

            else if (g[v[i]].size() > 1)
                c = v[i];
        }
    }
    
    memset(d, 0, sizeof d);

    d[c] = 1;

    for (auto i : g[c])
    {
        dfs(i);

        stc++;
    }

    sort(st, st+stc, [](vector <int> &x, vector <int> &y){return (x.size() < y.size());});

    for (int i = 0; i < stc; i++)
        fv[i] = st[i].size();
    
    l = 0;
    r = stc-1;

    while (st[r].size())
    {
        for (int i = r-1; st[r].size() && i >= l; i--)
        {
            ans[0].push_back(st[r].back());
            ans[1].push_back(st[i].back());

            st[r].pop_back();
            st[i].pop_back();
        }
        
        while (l < r && st[r].empty())
            r--;

        while (l < r && st[l].empty())
            l++;

        if (l == r && st[r].size())
        {
            if (int(st[r].size()) == fv[r])
            {
                ans[0].push_back(st[r].back());

                st[r].pop_back();
                    
                ans[1].push_back(c);
            }

            while (st[r].size())
            {
                ans[0].push_back(st[r].back());
                
                st[r].pop_back();
                
                if (st[r].size())
                {
                    ans[1].push_back(st[r].back());
                    st[r].pop_back();
                }

                else
                    ans[1].push_back(c);
            }
        }
    } 

    cout << ans[0].size() << "\n";

    for (int i = 0; i < int(ans[0].size()); i++)
        cout << ans[0][i] << " " << ans[1][i] << "\n";
}

Subtask #1
0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 32 ms 55148 KB Output is correct
2 Correct 26 ms 55196 KB Output is correct
3 Correct 25 ms 55156 KB Output is correct
4 Correct 26 ms 55156 KB Output is correct
5 Correct 26 ms 55088 KB Output is correct
6 Correct 31 ms 55136 KB Output is correct
7 Correct 25 ms 55156 KB Output is correct
8 Correct 29 ms 55028 KB Output is correct
9 Correct 31 ms 55124 KB Output is correct
10 Correct 25 ms 55036 KB Output is correct
11 Correct 28 ms 55180 KB Output is correct
12 Correct 29 ms 55068 KB Output is correct
13 Correct 26 ms 55124 KB Output is correct
14 Correct 26 ms 55152 KB Output is correct
15 Correct 26 ms 55156 KB Output is correct
16 Correct 29 ms 55124 KB Output is correct
17 Correct 28 ms 55108 KB Output is correct
18 Correct 32 ms 55080 KB Output is correct
19 Correct 28 ms 55124 KB Output is correct
20 Runtime error 68 ms 112188 KB Execution killed with signal 11
21 Halted 0 ms 0 KB -

Subtask #2
0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 32 ms 55148 KB Output is correct
2 Correct 26 ms 55196 KB Output is correct
3 Correct 25 ms 55156 KB Output is correct
4 Correct 26 ms 55156 KB Output is correct
5 Correct 26 ms 55088 KB Output is correct
6 Correct 31 ms 55136 KB Output is correct
7 Correct 25 ms 55156 KB Output is correct
8 Correct 29 ms 55028 KB Output is correct
9 Correct 31 ms 55124 KB Output is correct
10 Correct 25 ms 55036 KB Output is correct
11 Correct 28 ms 55180 KB Output is correct
12 Correct 29 ms 55068 KB Output is correct
13 Correct 26 ms 55124 KB Output is correct
14 Correct 26 ms 55152 KB Output is correct
15 Correct 26 ms 55156 KB Output is correct
16 Correct 29 ms 55124 KB Output is correct
17 Correct 28 ms 55108 KB Output is correct
18 Correct 32 ms 55080 KB Output is correct
19 Correct 28 ms 55124 KB Output is correct
20 Runtime error 68 ms 112188 KB Execution killed with signal 11
21 Halted 0 ms 0 KB -

Subtask #3
0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 32 ms 55148 KB Output is correct
2 Correct 26 ms 55196 KB Output is correct
3 Correct 25 ms 55156 KB Output is correct
4 Correct 26 ms 55156 KB Output is correct
5 Correct 26 ms 55088 KB Output is correct
6 Correct 31 ms 55136 KB Output is correct
7 Correct 25 ms 55156 KB Output is correct
8 Correct 29 ms 55028 KB Output is correct
9 Correct 31 ms 55124 KB Output is correct
10 Correct 25 ms 55036 KB Output is correct
11 Correct 28 ms 55180 KB Output is correct
12 Correct 29 ms 55068 KB Output is correct
13 Correct 26 ms 55124 KB Output is correct
14 Correct 26 ms 55152 KB Output is correct
15 Correct 26 ms 55156 KB Output is correct
16 Correct 29 ms 55124 KB Output is correct
17 Correct 28 ms 55108 KB Output is correct
18 Correct 32 ms 55080 KB Output is correct
19 Correct 28 ms 55124 KB Output is correct
20 Runtime error 68 ms 112188 KB Execution killed with signal 11
21 Halted 0 ms 0 KB -