Resolution for Double Cola Problem in Elixir

double_cola.ex

defmodule DoubleCola do
  defp mapper({current_names, size}),
    do: Enum.map(current_names, &(%{name: &1, size: size}))

  defp traverse([%{name: name, size: size} | rest], n) when n <= size,
    do: name
  defp traverse([%{name: name, size: size} | rest], n),
    do: traverse(rest, n - size)

  def find_nth(names, n) do
    names_length = length(names)
    range = Stream.unfold(1, &({&1, &1 * 2}))

    names
    |> Stream.cycle()
    |> Stream.chunk_every(names_length)
    |> Stream.zip(range)
    |> Stream.flat_map(&mapper/1)
    |> Enum.take(n)
    |> traverse(n)
  end
end