Submission #698112

#	Time	Username	Problem	Language	Result	Execution time	Memory
698112		finn__	RLE (BOI06_rle)	C++17	35 / 100	2593 ms	138268 KiB

rle

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

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    size_t n, m;
    cin >> n >> m;

    vector<pair<unsigned, uint64_t>> seq;
    unsigned e = 0;

    for (size_t i = 0; i < m; i++)
    {
        unsigned x;
        cin >> x;
        if (x == e)
        {
            i += 2;
            unsigned y, z;
            cin >> y >> z;
            if (y == e)
            { // Repeat e.
                if (!seq.empty() && seq.back().first == x)
                    seq.back().second += z + 1;
                else
                    seq.emplace_back(x, z + 1);
            }
            else
            {
                if (z)
                { // Repeat y.
                    if (!seq.empty() && seq.back().first == y)
                        seq.back().second += z + 3;
                    else
                        seq.emplace_back(y, z + 3);
                }
                else
                    e = y;
            }
        }
        else
        {
            if (!seq.empty() && seq.back().first == x)
                seq.back().second++;
            else
                seq.emplace_back(x, 1);
        }
    }

    vector<uint64_t> additional_cost(seq.size());

    for (size_t i = 0; i < seq.size(); i++)
    {
        auto const &[l, a] = seq[i];
        uint64_t c;
        if (a <= 3)
            c = a;
        else
            c = 3 * (a / (n + 3) + 1);
        additional_cost[i] = 3 * (a / (n + 1) + 1) - c;
    }

    priority_queue<pair<uint64_t, unsigned>, vector<pair<uint64_t, unsigned>>, greater<pair<uint64_t, unsigned>>> q;
    vector<uint64_t> dp(n, UINT_MAX);
    vector<vector<unsigned>> prev_letter(n), position(n);
    q.emplace(0, 0);
    dp[0] = 0;

    for (size_t i = 0; i < seq.size(); i++)
    {
        unsigned const l = seq[i].first;
        while (dp[q.top().second] != q.top().first || q.top().second == l)
            q.pop();

        if (q.top().first + 3 < dp[l] + additional_cost[i])
        {
            dp[l] = q.top().first + 3;
            prev_letter[l].push_back(q.top().second);
            position[l].push_back(i); // Means switch directly after i.
        }
        else
            dp[l] += additional_cost[i];

        q.emplace(dp[l], l);
    }

    while (q.top().first != dp[q.top().second])
        q.pop();
    vector<unsigned> code, switches, switch_positions;
    unsigned x = q.top().second, p = seq.size();
    while (1)
    {
        size_t i = lower_bound(position[x].begin(), position[x].end(), p) - position[x].begin();
        if (!i)
            break;
        unsigned y = prev_letter[x][i - 1];
        p = position[x][i - 1];
        switches.push_back(x);
        switch_positions.push_back(p);
        x = y;
    }

    reverse(switches.begin(), switches.end());
    reverse(switch_positions.begin(), switch_positions.end());
    e = 0;
    size_t j = 0;

    for (size_t i = 0; i < seq.size(); i++)
    {
        if (j < switches.size() && switch_positions[j] < i)
        {
            code.push_back(e);
            code.push_back(switches[j]);
            code.push_back(0);
            e = switches[j];
            j++;
        }

        if (seq[i].first != e)
        {
            while (seq[i].second > 3)
            {
                code.push_back(e);
                code.push_back(seq[i].first);
                code.push_back(min(seq[i].second - 3, n - 1));
                seq[i].second -= min(seq[i].second, n + 2);
            }
            if (seq[i].second)
            {
                for (size_t k = 0; k < seq[i].second; k++)
                    code.push_back(seq[i].first);
            }
        }
        else
        {
            while (seq[i].second)
            {
                code.push_back(e);
                code.push_back(e);
                code.push_back(min(seq[i].second - 1, n - 1));
                seq[i].second -= min(seq[i].second, n);
            }
        }
    }

    cout << code.size() << '\n';
    for (unsigned const &x : code)
        cout << x << ' ';
    cout << '\n';
}

• Subtask 1: 35 / 100