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답안 #656268

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
656268 2022-11-06T16:44:17 Z ilia_rr Network (BOI15_net) C++17
0 / 100
 74 ms 112236 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]]))
                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

# 결과 실행 시간 메모리 Grader output
1 Correct 27 ms 55116 KB Output is correct
2 Correct 30 ms 55144 KB Output is correct
3 Correct 33 ms 55124 KB Output is correct
4 Correct 27 ms 55160 KB Output is correct
5 Correct 31 ms 55116 KB Output is correct
6 Correct 26 ms 55048 KB Output is correct
7 Correct 26 ms 55156 KB Output is correct
8 Correct 26 ms 55080 KB Output is correct
9 Correct 27 ms 55116 KB Output is correct
10 Correct 28 ms 55132 KB Output is correct
11 Correct 26 ms 55156 KB Output is correct
12 Correct 26 ms 55020 KB Output is correct
13 Correct 26 ms 55156 KB Output is correct
14 Correct 25 ms 55144 KB Output is correct
15 Correct 27 ms 55124 KB Output is correct
16 Correct 26 ms 55088 KB Output is correct
17 Correct 26 ms 55124 KB Output is correct
18 Correct 26 ms 55124 KB Output is correct
19 Correct 25 ms 55124 KB Output is correct
20 Runtime error 74 ms 112236 KB Execution killed with signal 11
21 Halted 0 ms 0 KB -

Subtask #2
0 / 45.0

# 결과 실행 시간 메모리 Grader output
1 Correct 27 ms 55116 KB Output is correct
2 Correct 30 ms 55144 KB Output is correct
3 Correct 33 ms 55124 KB Output is correct
4 Correct 27 ms 55160 KB Output is correct
5 Correct 31 ms 55116 KB Output is correct
6 Correct 26 ms 55048 KB Output is correct
7 Correct 26 ms 55156 KB Output is correct
8 Correct 26 ms 55080 KB Output is correct
9 Correct 27 ms 55116 KB Output is correct
10 Correct 28 ms 55132 KB Output is correct
11 Correct 26 ms 55156 KB Output is correct
12 Correct 26 ms 55020 KB Output is correct
13 Correct 26 ms 55156 KB Output is correct
14 Correct 25 ms 55144 KB Output is correct
15 Correct 27 ms 55124 KB Output is correct
16 Correct 26 ms 55088 KB Output is correct
17 Correct 26 ms 55124 KB Output is correct
18 Correct 26 ms 55124 KB Output is correct
19 Correct 25 ms 55124 KB Output is correct
20 Runtime error 74 ms 112236 KB Execution killed with signal 11
21 Halted 0 ms 0 KB -

Subtask #3
0 / 37.0

# 결과 실행 시간 메모리 Grader output
1 Correct 27 ms 55116 KB Output is correct
2 Correct 30 ms 55144 KB Output is correct
3 Correct 33 ms 55124 KB Output is correct
4 Correct 27 ms 55160 KB Output is correct
5 Correct 31 ms 55116 KB Output is correct
6 Correct 26 ms 55048 KB Output is correct
7 Correct 26 ms 55156 KB Output is correct
8 Correct 26 ms 55080 KB Output is correct
9 Correct 27 ms 55116 KB Output is correct
10 Correct 28 ms 55132 KB Output is correct
11 Correct 26 ms 55156 KB Output is correct
12 Correct 26 ms 55020 KB Output is correct
13 Correct 26 ms 55156 KB Output is correct
14 Correct 25 ms 55144 KB Output is correct
15 Correct 27 ms 55124 KB Output is correct
16 Correct 26 ms 55088 KB Output is correct
17 Correct 26 ms 55124 KB Output is correct
18 Correct 26 ms 55124 KB Output is correct
19 Correct 25 ms 55124 KB Output is correct
20 Runtime error 74 ms 112236 KB Execution killed with signal 11
21 Halted 0 ms 0 KB -