Submission #732218

#	Time	Username	Problem	Language	Result	Execution time	Memory
732218		finn__	Nafta (COI15_nafta)	C++17	100 / 100	477 ms	84156 KiB

nafta

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

constexpr size_t N = 2001;
constexpr int di[4] = {1, 0, -1, 0}, dj[4] = {0, 1, 0, -1};

string grid[N];
unsigned comp[N][N], rlm[N * N];
int64_t val[N * N], w[N][N], f[N][N], g[N];

void dcdp(size_t a, size_t b, size_t u, size_t v, size_t j)
{
    size_t mid = (a + b) / 2, opt_i = u;
    for (size_t i = u; i <= v && i < mid; ++i)
        if (f[j - 1][i] + w[mid - 1][mid - 1] - (i ? w[i - 1][mid - 1] : 0) > f[j][mid])
            f[j][mid] = f[j - 1][i] + w[mid - 1][mid - 1] - (i ? w[i - 1][mid - 1] : 0),
            opt_i = i;
    if (a != b)
    {
        dcdp(a, (a + b) / 2, u, opt_i, j);
        dcdp((a + b) / 2 + 1, b, opt_i, v, j);
    }
}

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

    size_t n, m;
    cin >> n >> m;
    for (size_t i = 0; i < n; ++i)
        cin >> grid[i];

    memset(comp, 255, sizeof comp);
    size_t c = 0;
    for (size_t i = 0; i < n; ++i)
        for (size_t j = 0; j < m; ++j)
            if (comp[i][j] == UINT_MAX && grid[i][j] != '.')
            {
                queue<pair<unsigned, unsigned>> q({{i, j}});
                comp[i][j] = c;
                val[c] = grid[i][j] - '0';
                rlm[c] = j;
                while (!q.empty())
                {
                    auto const [u, v] = q.front();
                    q.pop();
                    for (size_t k = 0; k < 4; ++k)
                        if (u + di[k] < n && v + dj[k] < m && grid[u + di[k]][v + dj[k]] != '.' &&
                            comp[u + di[k]][v + dj[k]] == UINT_MAX)
                        {
                            comp[u + di[k]][v + dj[k]] = c;
                            val[c] += grid[u + di[k]][v + dj[k]] - '0';
                            rlm[c] = max(rlm[c], v + dj[k]);
                            q.emplace(u + di[k], v + dj[k]);
                        }
                }
                ++c;
            }

    for (size_t j = 0; j < m; ++j)
    {
        vector<unsigned> components;
        for (size_t i = 0; i < n; ++i)
            if (comp[i][j] != UINT_MAX)
                components.push_back(comp[i][j]);
        sort(components.begin(), components.end());
        components.resize(unique(components.begin(), components.end()) - components.begin());
        int64_t x = 0;
        for (unsigned const &u : components)
            x += val[u];
        w[j][j] = x;
        sort(components.begin(), components.end(), [](auto const &a, auto const &b)
             { return rlm[a] < rlm[b]; });
        auto it = components.begin();
        for (size_t k = j + 1; k < m; ++k)
        {
            while (it != components.end() && rlm[*it] < k)
                x -= val[*it], ++it;
            w[j][k] = x;
        }
    }

    for (size_t j = 1; j <= m; ++j)
        dcdp(1, m, 0, m - 1, j), cout << *max_element(f[j] + 1, f[j] + 1 + m) << '\n';
}

• Subtask 1: 11 / 11
• Subtask 2: 23 / 23
• Subtask 3: 66 / 66