Submission #668722

#	Time	Username	Problem	Language	Result	Execution time	Memory
668722		finn__	Sailing Race (CEOI12_race)	C++17	75 / 100	2559 ms	4400 KiB

race

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

size_t n;
bool swapped = 0;
vector<vector<bool>> g;
vector<vector<unsigned>> c, cc, longest;
unsigned max_length = 0, start = -1;

void longest_route()
{
    for (size_t i = 0; i < n; i++)
    {
        for (size_t j = i + 1; j < i + n; j++)
        {
            if (longest[i][j % n])
            {
                unsigned a = -1;
                for (size_t k = j + 1; k < i + n; k++)
                {
                    if (g[k % n][i])
                    {
                        a = k;
                        break;
                    }
                }

                if (a == UINT_MAX)
                    continue;

                for (size_t k = a + 1; k < i + n; k++)
                {
                    if (g[j % n][k % n])
                    {
                        unsigned l = 2 + longest[i][j % n] + max(cc[k % n][i], c[k % n][a % n]);
                        if (l > max_length)
                        {
                            max_length = l;
                            start = swapped ? (n - (a % n)) : (a % n) + 1;
                        }
                    }
                }
            }
        }
    }
}

void compute_c_cc()
{
    c = vector<vector<unsigned>>(n, vector<unsigned>(n, 0));
    cc = vector<vector<unsigned>>(n, vector<unsigned>(n, 0));

    for (size_t l = 2; l < n; l++)
    {
        for (size_t i = 0; i < n; i++)
        {
            size_t const j = (i + l) % n;

            for (size_t k = i + 1; k < i + l; k++)
            {
                if (g[i][k % n])
                    cc[i][j] =
                        max(cc[i][j], max(cc[k % n][j], c[k % n][i]) + 1);

                if (g[j][k % n])
                    c[j][i] =
                        max(c[j][i], max(cc[k % n][j], c[k % n][i]) + 1);

                if (g[j][i] && cc[i][j] + 1 > max_length)
                {
                    max_length = cc[i][j] + 1;
                    start = j + 1;
                }

                if (g[i][j] && c[j][i] + 1 > max_length)
                {
                    max_length = c[j][i] + 1;
                    start = i + 1;
                }
            }
        }
    }
}

void compute_longest()
{
    longest = vector<vector<unsigned>>(n, vector<unsigned>(n, 0));

    for (size_t l = 1; l < n; l++)
    {
        for (size_t i = 0; i < n; i++)
        {
            size_t const j = (i + l) % n;
            if (g[i][j])
                longest[i][j] = 1;

            for (size_t k = i + 1; k < i + l; k++)
            {
                if (longest[i][k % n] && longest[k % n][j])
                    longest[i][j] = max(longest[i][j], longest[i][k % n] + longest[k % n][j]);
            }
        }
    }
}

int main()
{
    size_t k;
    cin >> n >> k;

    g = vector<vector<bool>>(n, vector<bool>(n, 0));
    for (size_t i = 0; i < n; i++)
    {
        unsigned v;
        cin >> v;
        while (v)
        {
            g[i][v - 1] = 1;
            cin >> v;
        }
    }

    compute_c_cc();

    if (k == 0)
    {
        cout << max_length << '\n'
             << start << '\n';
        return 0;
    }

    compute_longest();
    longest_route();

    vector<bool> &y = g.back();
    for (size_t i = 0; i < n; i++)
        swap(y, g[i]);

    swapped = 1;
    compute_c_cc();
    compute_longest();
    longest_route();

    cout << max_length << '\n'
         << start << '\n';
}

• Subtask 1: 75 / 100