defmodule ArmstrongNumber do
  @moduledoc """
  Provides a way to validate whether or not a number is an Armstrong number
  """

  @spec valid?(integer) :: boolean
  def valid?(number) do
    digits = Integer.digits(number)
    n = length(digits)

    number == Enum.reduce(digits, 0, &(&1 ** n + &2))
  end
end