# -*- coding: utf-8 -*-
class Stack(object):
  """栈的实现类"""
  def __init__(self):
    self.__items = []
  # push(item) 添加一个新的元素item到栈顶
  def push(self, item):
    self.__items.append(item)
  # pop() 弹出栈顶元素
  def pop(self):
    return self.__items.pop()
  # peek() 返回栈顶元素
  def peek(self):
    return self.__items[self.size() - 1]
  # is_empty() 判断栈是否为空
  def is_empty(self):
    return self.__items == []
  # size() 返回栈的元素个数
  def size(self):
    return len(self.__items)
if __name__ == '__main__':
  stack = Stack()
  stack.push(2)
  stack.push(3)
  stack.push(4)
  stack.push(5)
  tmp = stack.pop()
  print(tmp)
  print(stack.peek())
  print(stack.size())
  print(stack.is_empty())

# -*- coding: utf-8 -*-
class Queue(object):
  """队列的实现"""
  def __init__(self):
    self.__items = []
  # push(item) 往队列中添加一个item元素
  def push(self, item):
    self.__items.insert(0, item)
  # pop() 从队列头部删除一个元素
  def pop(self):
    return self.__items.pop()
  # is_empty() 判断一个队列是否为空
  def is_empty(self):
    return self.__items == []
  # size() 返回队列的大小
  def size(self):
    return len(self.__items)
if __name__ == '__main__':
  queue = Queue()
  queue.push(1)
  queue.push(2)
  queue.push(3)
  queue.push(4)
  print(queue.pop())
  print(queue.pop())
  print(queue.pop())
  print(queue.size())
  print(queue.is_empty())

# -*- coding: utf-8 -*-
class Deque(object):
  """双端队列"""
  def __init__(self):
    self.__items = []
  # add_front(item) 从队头加入一个item元素
  def add_front(self, item):
    self.__items.insert(0, item)
  # add_rear(item) 从队尾加入一个item元素
  def add_rear(self, item):
    self.__items.append(item)
  # remove_front() 从队头删除一个item元素
  def remove_front(self):
    return self.__items.pop(0)
  # remove_rear() 从队尾删除一个item元素
  def remove_rear(self):
    return self.__items.pop()
  # is_empty() 判断双端队列是否为空
  def is_empty(self):
    return self.__items == []
  # size() 返回队列的大小
  def size(self):
    return len(self.__items)
  def print_items(self):
    print(self.__items)
if __name__ == '__main__':
  deque = Deque()
  deque.add_front(1)
  deque.add_front(3)
  deque.add_front(5)
  deque.print_items()
  deque.add_rear(9)
  deque.add_rear(8)
  deque.add_rear(7)
  deque.print_items()
  print(deque.is_empty())
  print(deque.remove_front())
  print(deque.remove_rear())
  deque.print_items()