kaladont.exs

words = File.read!("input.txt") |> String.split

defmodule A do
  def get(words, beginning, sequence) do
    if words[beginning] do
      words[beginning] |> Enum.filter(fn word ->
        !Enum.member?(sequence, word)
      end)
    end
  end

  def kalodont(words, sequence) do
    selected_words = get(words, sequence |> List.last |> String.slice(-2, 2), sequence)

    if selected_words && !Enum.empty?(selected_words) do
      selected_words |> Enum.each(fn word ->
        kalodont(words, sequence ++ [word])
      end)
    else
      IO.puts "******* NEW BIGGEST SEQUENCE WITH #{sequence |> Enum.count} CHARACTERS *********"
      File.write("sequence1.txt", sequence |> Enum.join(" "))
    end
  end
end

words_indexed_by_beginning = Enum.group_by(words, fn e -> String.slice(e, 0, 2) end)

Enum.each(words, fn word ->
  A.kalodont(words_indexed_by_beginning, [word])
end)