
class Dictionary

  def search(key);end

  def insert(item);end

  def delete(item);end

  def max;end

  def min;end

  # predecessor
  def pred(key);end

  # successor
  def succ(key);end

end

class PriorityQueue

  def insert(item);end

  def find_min;end

  def find_max;end

  def del_min;end

  def del_max;end

end
