Submission #343076

#	Time	Username	Problem	Language	Result	Execution time	Memory
343076		KoD	Skyscraper (JOI16_skyscraper)	C++17	100 / 100	78 ms	2904 KiB

skyscraper

#line 1 "main.cpp"

/**
 * @title Template
 */

#include <iostream>
#include <algorithm>
#include <utility>
#include <numeric>
#include <vector>
#include <array>
#include <cassert>

#line 2 "/Users/kodamankod/Desktop/cpp_programming/Library/other/range.cpp"

#line 4 "/Users/kodamankod/Desktop/cpp_programming/Library/other/range.cpp"

class range {
  struct iter {
    std::size_t itr;
    constexpr iter(std::size_t pos) noexcept: itr(pos) { }
    constexpr void operator ++ () noexcept { ++itr; }
    constexpr bool operator != (iter other) const noexcept { return itr != other.itr; }
    constexpr std::size_t operator * () const noexcept { return itr; }
  };

  struct reviter {
    std::size_t itr;
    constexpr reviter(std::size_t pos) noexcept: itr(pos) { }
    constexpr void operator ++ () noexcept { --itr; }
    constexpr bool operator != (reviter other) const noexcept { return itr != other.itr; }
    constexpr std::size_t operator * () const noexcept { return itr; }
  };

  const iter first, last;

public:
  constexpr range(std::size_t first, std::size_t last) noexcept: first(first), last(std::max(first, last)) { }
  constexpr iter begin() const noexcept { return first; }
  constexpr iter end() const noexcept { return last; }
  constexpr reviter rbegin() const noexcept { return reviter(*last - 1); } 
  constexpr reviter rend() const noexcept { return reviter(*first - 1); } 
};

/**
 * @title Range
 */
#line 2 "/Users/kodamankod/Desktop/cpp_programming/Library/algebraic/modular.cpp"

#line 2 "/Users/kodamankod/Desktop/cpp_programming/Library/algebraic/mod_inv.cpp"

#line 4 "/Users/kodamankod/Desktop/cpp_programming/Library/algebraic/mod_inv.cpp"
#include <cstdint>

constexpr std::pair<int64_t, int64_t> mod_inv(int64_t a, int64_t b) {
  if ((a %= b) == 0) return { b, 0 };
  int64_t s = b, t = (a < 0 ? a + b : a);
  int64_t m0 = 0, m1 = 1, tmp = 0;
  while (t > 0) {
    const auto u = s / t;
    s -= t * u; m0 -= m1 * u;
    tmp = s; s = t; t = tmp; tmp = m0; m0 = m1; m1 = tmp;
  }
  return { s, (m0 < 0 ? m0 + b / s : m0) };
}

/**
 * @title Extended GCD
 */
#line 4 "/Users/kodamankod/Desktop/cpp_programming/Library/algebraic/modular.cpp"

#line 8 "/Users/kodamankod/Desktop/cpp_programming/Library/algebraic/modular.cpp"
#include <type_traits>

template <class Modulus>
class modular {
public:
  using value_type = uint32_t;
  using cover_type = uint64_t;
 
  static constexpr uint32_t mod() { return Modulus::mod(); }
  template <class T>
  static constexpr value_type normalize(T value_) noexcept {
    if (value_ < 0) {
      value_ = -value_;
      value_ %= mod();
      if (value_ == 0) return 0;
      return mod() - value_;
    }
    return value_ % mod();
  }

private:
  value_type value;

  template <bool IsPrime, std::enable_if_t<IsPrime>* = nullptr>
  constexpr modular inverse_helper() const noexcept { return power(*this, mod() - 2); }
  template <bool IsPrime, std::enable_if_t<!IsPrime>* = nullptr>
  constexpr modular inverse_helper() const noexcept {
    const auto tmp = mod_inv(value, mod());
    assert(tmp.first == 1);
    return modular(tmp.second);
  }

public:
  constexpr modular() noexcept : value(0) { }
  template <class T>
  explicit constexpr modular(T value_) noexcept : value(normalize(value_)) { }
  template <class T>
  explicit constexpr operator T() const noexcept { return static_cast<T>(value); }
 
  constexpr value_type get() const noexcept { return value; }
  constexpr value_type &extract() noexcept { return value; }
  constexpr modular operator - () const noexcept { return modular(mod() - value); }
  constexpr modular operator ~ () const noexcept { return inverse(*this); }
 
  constexpr modular operator + (const modular &rhs) const noexcept { return modular(*this) += rhs; }
  constexpr modular& operator += (const modular &rhs) noexcept { 
    if ((value += rhs.value) >= mod()) value -= mod(); 
    return *this; 
  }
 
  constexpr modular operator - (const modular &rhs) const noexcept { return modular(*this) -= rhs; }
  constexpr modular& operator -= (const modular &rhs) noexcept { 
    if ((value += mod() - rhs.value) >= mod()) value -= mod(); 
    return *this; 
  }
 
  constexpr modular operator * (const modular &rhs) const noexcept { return modular(*this) *= rhs; }
  constexpr modular& operator *= (const modular &rhs) noexcept { 
    value = (cover_type) value * rhs.value % mod();
    return *this;
  }
 
  constexpr modular operator / (const modular &rhs) const noexcept { return modular(*this) /= rhs; }
  constexpr modular& operator /= (const modular &rhs) noexcept { return (*this) *= inverse(rhs); }
 
  constexpr bool zero() const noexcept { return value == 0; }
  constexpr bool operator == (const modular &rhs) const noexcept { return value == rhs.value; }
  constexpr bool operator != (const modular &rhs) const noexcept { return value != rhs.value; }
 
  friend std::ostream& operator << (std::ostream &stream, const modular &rhs) { return stream << rhs.value; }
  friend constexpr modular inverse(const modular &val) noexcept { return val.inverse_helper<Modulus::is_prime>(); }
  friend constexpr modular power(modular val, cover_type exp) noexcept { 
    modular res(1);
    for (; exp > 0; exp >>= 1, val *= val) if (exp & 1) res *= val;
    return res;
  }
 
};
 
template <uint32_t Mod, bool IsPrime = true>
struct static_modulus { 
  static constexpr uint32_t mod() noexcept { return Mod; } 
  static constexpr bool is_prime = IsPrime;
};

template <uint32_t Id = 0, bool IsPrime = false>
struct dynamic_modulus {
  static uint32_t &mod() noexcept { static uint32_t val = 0; return val; }
  static constexpr bool is_prime = IsPrime;
};

template <uint32_t Mod, bool IsPrime = true>
using mint32_t = modular<static_modulus<Mod, IsPrime>>;
using rmint32_t = modular<dynamic_modulus<>>;

/*
 * @title Modint
 */
#line 16 "main.cpp"

using i32 = std::int32_t;
using i64 = std::int64_t;
using u32 = std::uint32_t;
using u64 = std::uint64_t;
using isize = std::ptrdiff_t;
using usize = std::size_t;

constexpr i32 inf32 = (u32) ~0 >> 2;
constexpr i64 inf64 = (u64) ~0 >> 2;

template <class T>
using Vec = std::vector<T>;

using Fp = mint32_t<1000000007>;

int main() {
  usize N;
  u32 L;
  std::cin >> N >> L;
  Vec<u32> A(N);
  for (auto &x: A) {
    std::cin >> x;
  }
  if (N == 1) {
    std::cout << 1 << '\n';
    return 0;
  }
  std::sort(A.begin(), A.end());
  Vec<Vec<std::array<Fp, 3>>> dp(N + 1, Vec<std::array<Fp, 3>>(L + 1));
  dp[0][0][0] = Fp(1);
  for (auto i: range(0, N)) {
    const auto cost = (i == 0 ? 0 : A[i] - A[i - 1]);
    Vec<Vec<std::array<Fp, 3>>> next(N + 1, Vec<std::array<Fp, 3>>(L + 1));
    for (auto j: range(0, N + 1)) {
      for (auto k: range(0, L + 1)) {
        for (auto l: range(0, 3)) {
          const auto val = dp[j][k][l];
          if (val.zero()) {
            continue;
          }
          const auto nk = k + (2 * j - l) * cost;
          if (nk > L) {
            continue;
          }
          if (l < 2) {
            if (j > 0) {
              next[j][nk][l + 1] += val * Fp(2 - l);
            }
            if (j < N) {
              next[j + 1][nk][l + 1] += val * Fp(2 - l);
            }
          }
          if (j > 0) {
            next[j][nk][l] += val * Fp(2 * j - l);
          }
          if (j > 1) {
            next[j - 1][nk][l] += val * Fp(j - 1);
          }
          if (j < N) {
            next[j + 1][nk][l] += val * Fp(j + 1 - l);
          }
        }
      }
    }
    dp = std::move(next);
  }
  Fp ans;
  for (auto i: range(0, L + 1)) {
    ans += dp[1][i][2];
  }
  std::cout << ans << '\n';
  return 0;
}

• Subtask 1: 5 / 5
• Subtask 2: 15 / 15
• Subtask 3: 80 / 80