oj.uz

Submission #656275

# Submission time Handle Problem Language Result Execution time Memory
656275 2022-11-06T16:59:17 Z ilia_rr Network (BOI15_net) C++17
0 / 100
 70 ms 112248 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 (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[v[i]].size() == 1)
                c = u[i];

            else
                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 25 ms 55124 KB Output is correct
2 Correct 28 ms 55052 KB Output is correct
3 Correct 28 ms 55152 KB Output is correct
4 Correct 27 ms 55124 KB Output is correct
5 Correct 25 ms 55124 KB Output is correct
6 Correct 26 ms 55136 KB Output is correct
7 Correct 26 ms 55084 KB Output is correct
8 Correct 26 ms 55128 KB Output is correct
9 Correct 27 ms 55136 KB Output is correct
10 Correct 29 ms 55124 KB Output is correct
11 Correct 26 ms 55064 KB Output is correct
12 Correct 25 ms 55152 KB Output is correct
13 Correct 27 ms 55108 KB Output is correct
14 Correct 25 ms 55012 KB Output is correct
15 Correct 26 ms 55128 KB Output is correct
16 Correct 26 ms 55124 KB Output is correct
17 Correct 26 ms 55092 KB Output is correct
18 Correct 26 ms 55152 KB Output is correct
19 Correct 26 ms 55124 KB Output is correct
20 Runtime error 70 ms 112248 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 25 ms 55124 KB Output is correct
2 Correct 28 ms 55052 KB Output is correct
3 Correct 28 ms 55152 KB Output is correct
4 Correct 27 ms 55124 KB Output is correct
5 Correct 25 ms 55124 KB Output is correct
6 Correct 26 ms 55136 KB Output is correct
7 Correct 26 ms 55084 KB Output is correct
8 Correct 26 ms 55128 KB Output is correct
9 Correct 27 ms 55136 KB Output is correct
10 Correct 29 ms 55124 KB Output is correct
11 Correct 26 ms 55064 KB Output is correct
12 Correct 25 ms 55152 KB Output is correct
13 Correct 27 ms 55108 KB Output is correct
14 Correct 25 ms 55012 KB Output is correct
15 Correct 26 ms 55128 KB Output is correct
16 Correct 26 ms 55124 KB Output is correct
17 Correct 26 ms 55092 KB Output is correct
18 Correct 26 ms 55152 KB Output is correct
19 Correct 26 ms 55124 KB Output is correct
20 Runtime error 70 ms 112248 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 25 ms 55124 KB Output is correct
2 Correct 28 ms 55052 KB Output is correct
3 Correct 28 ms 55152 KB Output is correct
4 Correct 27 ms 55124 KB Output is correct
5 Correct 25 ms 55124 KB Output is correct
6 Correct 26 ms 55136 KB Output is correct
7 Correct 26 ms 55084 KB Output is correct
8 Correct 26 ms 55128 KB Output is correct
9 Correct 27 ms 55136 KB Output is correct
10 Correct 29 ms 55124 KB Output is correct
11 Correct 26 ms 55064 KB Output is correct
12 Correct 25 ms 55152 KB Output is correct
13 Correct 27 ms 55108 KB Output is correct
14 Correct 25 ms 55012 KB Output is correct
15 Correct 26 ms 55128 KB Output is correct
16 Correct 26 ms 55124 KB Output is correct
17 Correct 26 ms 55092 KB Output is correct
18 Correct 26 ms 55152 KB Output is correct
19 Correct 26 ms 55124 KB Output is correct
20 Runtime error 70 ms 112248 KB Execution killed with signal 11
21 Halted 0 ms 0 KB -