Alchemist Camp

guessing_game.ex

defmodule GuessingGame do
  def guess(a, b) when a > b, do: guess(b, a)

  def guess(low, high) do
    answer = IO.gets("Maybe you thinking of #{mid(low, high)}? ")

    case String.trim(answer) do
      "bigger" ->
        bigger(low, high)

      "smaller" ->
        smaller(low, high)

      "yes" ->
        IO.puts("Horay! 🥳 🎉 🎊")

      _ ->
        IO.puts(~s(Type "bigger", "smaller" or "yes"))
        guess(low, high)
    end
  end

  defp mid(low, high) do
    div(low + high, 2)
  end

  defp bigger(low, high) do
    new_low = min(high, mid(low, high) + 1)
    guess(new_low, high)
  end

  defp smaller(low, high) do
    new_high = max(low, mid(low, high) - 1)
    guess(low, new_high)
  end
end