[Python]python算法入门 -- 栈（stack）

读书笔记

Stack : LIFO last-in first-out

生活中的例子：放书，浏览器记录等

stack通常的操作：
Stack() 建立一个空的栈对象
push() 把一个元素添加到栈的最顶层
pop() 删除栈最顶层的元素，并返回这个元素
peek() 返回最顶层的元素，并不删除它
isEmpty() 判断栈是否为空
size() 返回栈中元素的个数

简单案例以及操作结果：
[python]
Stack Operation           Stack Contents     Return Value
    s.isEmpty()     []                 True
    s.push(4)       [4]
    s.push('dog')       [4,'dog']
    s.peek()        [4,'dog']          'dog'
    s.push(True)        [4,'dog',True]
    s.size()        [4,'dog',True]      3
    s.isEmpty()     [4,'dog',True]      False
    s.push(8.4)     [4,'dog',True,8.4]
    s.pop()             [4,'dog',True]      8.4
    s.pop()             [4,'dog']           True
    s.size()        [4,'dog']           2

Stack Operation           Stack Contents     Return Value
s.isEmpty()     []                True
s.push(4)     [4]
s.push('dog')     [4,'dog']
s.peek()     [4,'dog']        'dog'
s.push(True)     [4,'dog',True]
s.size()     [4,'dog',True]     3
s.isEmpty()     [4,'dog',True]     False
s.push(8.4)     [4,'dog',True,8.4]
s.pop()             [4,'dog',True]     8.4
s.pop()             [4,'dog']         True
s.size()     [4,'dog']         2

这里使用python的list对象模拟栈的实现：
[python]
#coding:utf8
class Stack:
    """模拟栈"""
    def __init__(self):
        self.items = []

    def isEmpty(self):
        return len(self.items)==0

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

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

    def peek(self):
        if not self.isEmpty():
            return self.items[len(self.items)-1]

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


s=Stack()
print(s.isEmpty())
s.push(4)
s.push('dog')
print(s.peek())
s.push(True)
print(s.size())
print(s.isEmpty())
s.push(8.4)
print(s.pop())
print(s.pop())
print(s.size())

#coding:utf8
class Stack:
    """模拟栈"""
    def __init__(self):
        self.items = []

    def isEmpty(self):
        return len(self.items)==0

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

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

    def peek(self):
        if not self.isEmpty():
            return self.items[len(self.items)-1]

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


s=Stack()
print(s.isEmpty())
s.push(4)
s.push('dog')
print(s.peek())
s.push(True)
print(s.size())
print(s.isEmpty())
s.push(8.4)
print(s.pop())
print(s.pop())
print(s.size())

补充：Web开发 , Python ,