start = File.read!("inputs/day10.txt")

digitRegex = ~r/(\d)\1*/

lookAndSayStream =
  Stream.iterate(start, fn current ->
    Regex.scan(digitRegex, current)
    |> Enum.map(fn [seq, _] ->
      length = String.length(seq)
      type = String.at(seq, 0)
      "#{length}#{type}"
    end)
    |> Enum.join()
  end)

[fourtiethEntry] = Stream.drop(lookAndSayStream, 40) |> Enum.take(1)
IO.puts("Fourtieth Entry Length: #{String.length(fourtiethEntry)}")

[fiftiethEntry] = Stream.drop(lookAndSayStream, 50) |> Enum.take(1)
IO.puts("Fiftieth Entry Length: #{String.length(fiftiethEntry)}")