simple_queue.rb

# q can be unlimited length
# one var only
# each element is a single digit integer

class SingleVarQ
  def initialize(start)
    @q = start
  end

  def queue
    p @q
  end

  def enqueue num_to_queue
    unless num_to_queue > 9 || num_to_queue < 0
      @q == 0 ? @q = num_to_queue : @q = num_to_queue * 10**index(@q) + @q
    end
  end

  def dequeue
    @q /= 10
  end

  def circular_queue
    enqueue(@q % 10); dequeue
  end

  private
    def index(q)
      q < 10 ? 1 : Math.log10(q).ceil
    end
end