defmodule ABC do
  def can_make_word(word, avail) do
    can_make_word(String.upcase(word) |> to_charlist, avail, [])
  end

  defp can_make_word([], _, _), do: true
  defp can_make_word(_, [], _), do: false
  defp can_make_word([l|tail], [b|rest], tried) do
    (l in b and can_make_word(tail, rest++tried, []))
    or can_make_word([l|tail], rest, [b|tried])
  end
end

blocks = ~w(BO XK DQ CP NA GT RE TG QD FS JW HU VI AN OB ER FS LY PC ZM)c
~w(A Bark Book Treat Common Squad Confuse) |>
Enum.map(fn(w) -> IO.puts "#{w}: #{ABC.can_make_word(w, blocks)}" end)