数据结构之栈

#/usr/bin/env python2.7
# -*- coding: utf-8 -*-
"""
Create Time: 2020/07/25 8:25 PM
Author: ada
"""

class Stack:
	def __init__(self):
		self.items = []

	def isEmpty(self):
		return self.items == []
	''' 直接return == 来返回列表是否为空的逻辑条件'''

	def push(self,item):
		self.items.append(item)

	def pop(self):
		self.items.pop()

	def peek(self):
		return self.items[len(self.items)-1]

	def size(self):
		return len(self.items)

'''
后进先出
刚好python list ，append，每次都是右边添加元素，pop也是右边最新加入的元素
'''
s = Stack()
print s.isEmpty()
print s.push('one')
print s.push('two')
print s.peek()
print s.size()
print s.pop()
print s.size()