defmodule Frequent do
  def number( [num | tail] ) do
    number({num, 1}, tail, {num, 1})
  end

  def number({num, count}, [ num | tail ], max) do
    number({num, count + 1}, tail, max)
  end

  def number({_num, count} = current, [ diff | tail ], {_, max_count} = max) do
    if count > max_count do
      max = current
    end
    number({diff, 1}, tail, max)
  end

  def number(_, [], max), do: max
end