Library

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:heavy_check_mark: test/aoj/aoj_3086.test.cpp

Depends on

Code

#define PROBLEM "https://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=3086"

#include "../../algorithm/monge_shortest_path.hpp"
#include "../../data_structure/segtree.hpp"
#include "../../template/template.hpp"

namespace ebi {

i64 op(i64 a, i64 b) {
    return a < b ? a : b;
}

i64 e() {
    return LNF;
}

void main_() {
    int n, l;
    std::cin >> n >> l;
    std::vector<i64> a(n);
    std::cin >> a;
    rep(i, 0, n) a[i] = -a[i];
    segtree<i64, op, e> seg(a);
    auto f = [&](int i, int j) -> i64 {
        if (j - i < l) return std::numeric_limits<i64>::max();
        return seg.prod(i, j);
    };
    auto dp = monge_shortest_path(n + 1, f);
    std::cout << -dp[n] << '\n';
}

}  // namespace ebi

int main() {
    ebi::fast_io();
    int t = 1;
    // std::cin >> t;
    while (t--) {
        ebi::main_();
    }
    return 0;
}
#line 1 "test/aoj/aoj_3086.test.cpp"
#define PROBLEM "https://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=3086"

#line 2 "algorithm/monge_shortest_path.hpp"

#include <limits>
#include <vector>

namespace ebi {

template <class F, class T = decltype(std::declval<F>()(std::declval<int>(),
                                                        std::declval<int>()))>
std::vector<T> monge_shortest_path(int n, F f) {
    const T max = std::numeric_limits<T>::max();
    std::vector<int> argmin(n, 0);
    std::vector<T> dp(n, max);
    dp[0] = 0;
    auto get = [&](int i, int j) -> T {
        T val = f(j, i);
        if (val == max || dp[j] == max) return max;
        return dp[j] + val;
    };
    auto check = [&](int i, int j) -> void {
        T val = get(i, j);
        if (val < dp[i]) {
            dp[i] = val;
            argmin[i] = j;
        }
    };
    dp[n - 1] = get(n - 1, 0);
    auto dfs = [&](auto &&self, int l, int r) -> void {
        if (r - l == 1) return;
        int m = (l + r) >> 1;
        for (int i = argmin[l]; i <= argmin[r]; i++) {
            check(m, i);
        }
        self(self, l, m);
        for (int i = l + 1; i <= m; i++) {
            check(r, i);
        }
        self(self, m, r);
    };
    dfs(dfs, 0, n - 1);
    return dp;
}

}  // namespace ebi
#line 2 "data_structure/segtree.hpp"

#include <cassert>

#line 5 "data_structure/segtree.hpp"

namespace ebi {

template <class S, S (*op)(S, S), S (*e)()> struct segtree {
  private:
    int n;
    int sz;
    std::vector<S> data;

    void update(int i) {
        data[i] = op(data[2 * i], data[2 * i + 1]);
    }

  public:
    segtree(int n_) : segtree(std::vector<S>(n_, e())) {}
    segtree(const std::vector<S> &v) : n((int)v.size()), sz(1) {
        while (sz < n) sz *= 2;
        data = std::vector<S>(2 * sz, e());
        for (int i = 0; i < n; i++) {
            data[sz + i] = v[i];
        }
        for (int i = sz - 1; i >= 1; i--) update(i);
    }

    void set(int p, S x) {
        assert(0 <= p && p < n);
        p += sz;
        data[p] = x;
        while (p > 1) {
            p >>= 1;
            update(p);
        }
    }

    S get(int p) const {
        assert(0 <= p && p < n);
        return data[p + sz];
    }

    S prod(int l, int r) const {
        assert(0 <= l && l <= r && r <= n);
        S sml = e(), smr = e();
        l += sz;
        r += sz;
        while (l < r) {
            if (l & 1) sml = op(sml, data[l++]);
            if (r & 1) smr = op(data[--r], smr);
            l >>= 1;
            r >>= 1;
        }
        return op(sml, smr);
    }

    S all_prod() const {
        return data[1];
    }

    template <class F> int max_right(int l, F f) const {
        assert(0 <= l && l < n);
        assert(f(e()));
        if (l == n) return n;
        l += sz;
        S sm = e();
        do {
            while (l % 2 == 0) l >>= 1;
            if (!f(op(sm, data[l]))) {
                while (l < sz) {
                    l = 2 * l;
                    if (f(op(sm, data[l]))) {
                        sm = op(sm, data[l]);
                        l++;
                    }
                }
                return l - sz;
            }
            sm = op(sm, data[l]);
            l++;
        } while ((l & -l) != l);
        return n;
    }

    template <class F> int min_left(int r, F f) const {
        assert(0 <= r && r <= n);
        assert(f(e()));
        if (r == 0) return 0;
        r += sz;
        S sm = e();
        do {
            r--;
            while (r > 1 && (r % 2)) r >>= 1;
            if (!f(op(data[r], sm))) {
                while (r < sz) {
                    r = 2 * r + 1;
                    if (f(op(data[r], sm))) {
                        sm = op(data[r], sm);
                        r--;
                    }
                }
                return r + 1 - sz;
            }
            sm = op(data[r], sm);
        } while ((r & -r) != r);
        return 0;
    }

    S operator[](int p) const {
        return data[sz + p];
    }
};

}  // namespace ebi

#line 1 "template/template.hpp"
#include <bits/stdc++.h>

#define rep(i, a, n) for (int i = (int)(a); i < (int)(n); i++)
#define rrep(i, a, n) for (int i = ((int)(n)-1); i >= (int)(a); i--)
#define Rep(i, a, n) for (i64 i = (i64)(a); i < (i64)(n); i++)
#define RRep(i, a, n) for (i64 i = ((i64)(n)-i64(1)); i >= (i64)(a); i--)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()

#line 2 "template/debug_template.hpp"

#line 4 "template/debug_template.hpp"

namespace ebi {

#ifdef LOCAL
#define debug(...)                                                      \
    std::cerr << "LINE: " << __LINE__ << "  [" << #__VA_ARGS__ << "]:", \
        debug_out(__VA_ARGS__)
#else
#define debug(...)
#endif

void debug_out() {
    std::cerr << std::endl;
}

template <typename Head, typename... Tail> void debug_out(Head h, Tail... t) {
    std::cerr << " " << h;
    if (sizeof...(t) > 0) std::cerr << " :";
    debug_out(t...);
}

}  // namespace ebi
#line 2 "template/int_alias.hpp"

#line 4 "template/int_alias.hpp"

namespace ebi {

using ld = long double;
using std::size_t;
using i8 = std::int8_t;
using u8 = std::uint8_t;
using i16 = std::int16_t;
using u16 = std::uint16_t;
using i32 = std::int32_t;
using u32 = std::uint32_t;
using i64 = std::int64_t;
using u64 = std::uint64_t;
using i128 = __int128_t;
using u128 = __uint128_t;

}  // namespace ebi
#line 2 "template/io.hpp"

#line 5 "template/io.hpp"
#include <optional>
#line 7 "template/io.hpp"

namespace ebi {

template <typename T1, typename T2>
std::ostream &operator<<(std::ostream &os, const std::pair<T1, T2> &pa) {
    return os << pa.first << " " << pa.second;
}

template <typename T1, typename T2>
std::istream &operator>>(std::istream &os, std::pair<T1, T2> &pa) {
    return os >> pa.first >> pa.second;
}

template <typename T>
std::ostream &operator<<(std::ostream &os, const std::vector<T> &vec) {
    for (std::size_t i = 0; i < vec.size(); i++)
        os << vec[i] << (i + 1 == vec.size() ? "" : " ");
    return os;
}

template <typename T>
std::istream &operator>>(std::istream &os, std::vector<T> &vec) {
    for (T &e : vec) std::cin >> e;
    return os;
}

template <typename T>
std::ostream &operator<<(std::ostream &os, const std::optional<T> &opt) {
    if (opt) {
        os << opt.value();
    } else {
        os << "invalid value";
    }
    return os;
}

void fast_io() {
    std::cout << std::fixed << std::setprecision(15);
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);
}

}  // namespace ebi
#line 2 "template/utility.hpp"

#line 5 "template/utility.hpp"

#line 2 "graph/base.hpp"

#line 5 "graph/base.hpp"
#include <ranges>
#line 7 "graph/base.hpp"

#line 2 "data_structure/simple_csr.hpp"

#line 6 "data_structure/simple_csr.hpp"

namespace ebi {

template <class E> struct simple_csr {
    simple_csr() = default;

    simple_csr(int n, const std::vector<std::pair<int, E>>& elements)
        : start(n + 1, 0), elist(elements.size()) {
        for (auto e : elements) {
            start[e.first + 1]++;
        }
        for (auto i : std::views::iota(0, n)) {
            start[i + 1] += start[i];
        }
        auto counter = start;
        for (auto [i, e] : elements) {
            elist[counter[i]++] = e;
        }
    }

    simple_csr(const std::vector<std::vector<E>>& es)
        : start(es.size() + 1, 0) {
        int n = es.size();
        for (auto i : std::views::iota(0, n)) {
            start[i + 1] = (int)es[i].size() + start[i];
        }
        elist.resize(start.back());
        for (auto i : std::views::iota(0, n)) {
            std::copy(es[i].begin(), es[i].end(), elist.begin() + start[i]);
        }
    }

    int size() const {
        return (int)start.size() - 1;
    }

    const auto operator[](int i) const {
        return std::ranges::subrange(elist.begin() + start[i],
                                     elist.begin() + start[i + 1]);
    }
    auto operator[](int i) {
        return std::ranges::subrange(elist.begin() + start[i],
                                     elist.begin() + start[i + 1]);
    }

    const auto operator()(int i, int l, int r) const {
        return std::ranges::subrange(elist.begin() + start[i] + l,
                                     elist.begin() + start[i + 1] + r);
    }
    auto operator()(int i, int l, int r) {
        return std::ranges::subrange(elist.begin() + start[i] + l,
                                     elist.begin() + start[i + 1] + r);
    }

  private:
    std::vector<int> start;
    std::vector<E> elist;
};

}  // namespace ebi
#line 9 "graph/base.hpp"

namespace ebi {

template <class T> struct Edge {
    int from, to;
    T cost;
    int id;
};

template <class E> struct Graph {
    using cost_type = E;
    using edge_type = Edge<cost_type>;

    Graph(int n_) : n(n_) {}

    Graph() = default;

    void add_edge(int u, int v, cost_type c) {
        buff.emplace_back(u, edge_type{u, v, c, m});
        edges.emplace_back(edge_type{u, v, c, m++});
    }

    void add_undirected_edge(int u, int v, cost_type c) {
        buff.emplace_back(u, edge_type{u, v, c, m});
        buff.emplace_back(v, edge_type{v, u, c, m});
        edges.emplace_back(edge_type{u, v, c, m});
        m++;
    }

    void read_tree(int offset = 1, bool is_weighted = false) {
        read_graph(n - 1, offset, false, is_weighted);
    }

    void read_parents(int offset = 1) {
        for (auto i : std::views::iota(1, n)) {
            int p;
            std::cin >> p;
            p -= offset;
            add_undirected_edge(p, i, 1);
        }
        build();
    }

    void read_graph(int e, int offset = 1, bool is_directed = false,
                    bool is_weighted = false) {
        for (int i = 0; i < e; i++) {
            int u, v;
            std::cin >> u >> v;
            u -= offset;
            v -= offset;
            if (is_weighted) {
                cost_type c;
                std::cin >> c;
                if (is_directed) {
                    add_edge(u, v, c);
                } else {
                    add_undirected_edge(u, v, c);
                }
            } else {
                if (is_directed) {
                    add_edge(u, v, 1);
                } else {
                    add_undirected_edge(u, v, 1);
                }
            }
        }
        build();
    }

    void build() {
        assert(!prepared);
        csr = simple_csr<edge_type>(n, buff);
        buff.clear();
        prepared = true;
    }

    int size() const {
        return n;
    }

    int node_number() const {
        return n;
    }

    int edge_number() const {
        return m;
    }

    edge_type get_edge(int i) const {
        return edges[i];
    }

    std::vector<edge_type> get_edges() const {
        return edges;
    }

    const auto operator[](int i) const {
        return csr[i];
    }
    auto operator[](int i) {
        return csr[i];
    }

  private:
    int n, m = 0;

    std::vector<std::pair<int,edge_type>> buff;

    std::vector<edge_type> edges;
    simple_csr<edge_type> csr;
    bool prepared = false;
};

}  // namespace ebi
#line 8 "template/utility.hpp"

namespace ebi {

template <class T> inline bool chmin(T &a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}

template <class T> inline bool chmax(T &a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

template <class T> T safe_ceil(T a, T b) {
    if (a % b == 0)
        return a / b;
    else if (a >= 0)
        return (a / b) + 1;
    else
        return -((-a) / b);
}

template <class T> T safe_floor(T a, T b) {
    if (a % b == 0)
        return a / b;
    else if (a >= 0)
        return a / b;
    else
        return -((-a) / b) - 1;
}

constexpr i64 LNF = std::numeric_limits<i64>::max() / 4;

constexpr int INF = std::numeric_limits<int>::max() / 2;

const std::vector<int> dy = {1, 0, -1, 0, 1, 1, -1, -1};
const std::vector<int> dx = {0, 1, 0, -1, 1, -1, 1, -1};

}  // namespace ebi
#line 6 "test/aoj/aoj_3086.test.cpp"

namespace ebi {

i64 op(i64 a, i64 b) {
    return a < b ? a : b;
}

i64 e() {
    return LNF;
}

void main_() {
    int n, l;
    std::cin >> n >> l;
    std::vector<i64> a(n);
    std::cin >> a;
    rep(i, 0, n) a[i] = -a[i];
    segtree<i64, op, e> seg(a);
    auto f = [&](int i, int j) -> i64 {
        if (j - i < l) return std::numeric_limits<i64>::max();
        return seg.prod(i, j);
    };
    auto dp = monge_shortest_path(n + 1, f);
    std::cout << -dp[n] << '\n';
}

}  // namespace ebi

int main() {
    ebi::fast_io();
    int t = 1;
    // std::cin >> t;
    while (t--) {
        ebi::main_();
    }
    return 0;
}
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