Array_remove.rb

class Array
  def remove(items_to_delete)
    lut	= Hash.new(0)
    items_to_delete.each do |e| lut[e] += 1 end
    result = []
    each do |e|
      if lut[e] > 0
        lut[e] -= 1
      else
        result << e
      end
    end

    result
  end

  def remove!(*args)
    replace(remove(*args))
  end
end