#601908 (Crystal) No.1331 Moving Penguin

• 問題: No.1331 Moving Penguin
• ユーザー: yuruhiya
• 提出日時: 2021-01-09 16:16:20
• 言語: Crystal (1.14.0)
• 結果: AC
• 実行時間: 359 ms / 1,500 ms
• コード長: 1,795 bytes
• コンパイル時間: 13,614 ms
• コンパイル使用メモリ: 295,464 KB
• 実行使用メモリ: 10,796 KB
• 最終ジャッジ日時: 2024-11-07 15:05:31
• 合計ジャッジ時間: 26,594 ms
• ジャッジサーバーID （参考情報）: judge3 / judge4

ファイルパターン	結果
other	AC * 49

ソースコード

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lib C
  fun strtoll(s : UInt8*, p : UInt8**, b : Int32) : Int64
end
class String
  def to_i64
    C.strtoll(self, nil, 10)
  end
end
struct Mint
  @@MOD = 1_000_000_007i64
  def self.mod
    @@MOD
  end
  def self.zero
    Mint.new(0)
  end
  def initialize(n)
    @n = n.to_i64 % @@MOD
  end
  getter n : Int64
  def + : self
    self
  end
  def - : self
    Mint.new(n != 0 ? @@MOD - @n : 0)
  end
  def +(m)
    Mint.new(@n + m.to_i64 % @@MOD)
  end
  def -(m)
    Mint.new(@n - m.to_i64 % @@MOD)
  end
  def *(m)
    Mint.new(@n * m.to_i64 % @@MOD)
  end
  def /(m)
    raise DivisionByZeroError.new if m == 0
    a, b, u, v = m.to_i64, @@MOD, 1i64, 0i64
    while b != 0
      t = a // b
      a -= t * b
      a, b = b, a
      u -= t * v
      u, v = v, u
    end
    Mint.new(@n * u)
  end
  def //(m)
    self / m
  end
  def **(m : Int)
    t, res = self, Mint.new(1)
    while m > 0
      res *= t if m.odd?
      t *= t
      m >>= 1
    end
    res
  end
  def ==(m)
    @n == m.to_i64
  end
  def !=(m)
    @n != m.to_i64
  end
  def succ
    self + 1
  end
  def pred
    self - 1
  end
  def to_i64 : Int64
    @n
  end
  delegate to_s, to: @n
  delegate inspect, to: @n
end
struct Int
  def to_mint : Mint
    Mint.new(self)
  end
end
class String
  def to_mint : Mint
    Mint.new(self)
  end
end
n = read_line.to_i
a = read_line.split.map(&.to_i)
sqrt_n = Math.sqrt(n).to_i
plus = Array.new(sqrt_n) { |i| [Mint.zero] * i }
dp = [Mint.zero] * n
dp[0] = Mint.new(1)
(0...n).each do |i|
  (1...sqrt_n).each do |x|
    dp[i] += plus[x][i % x]
  end
  if a[i] < sqrt_n
    plus[a[i]][i % a[i]] += dp[i]
  else
    (i + a[i]...n).step(a[i]) { |j|
      dp[j] += dp[i]
    }
  end
  if i + 1 < n && a[i] > 1
    dp[i + 1] += dp[i]
  end
end
puts dp[n - 1]
 
 
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