python栈--字符串反转，括号匹配

栈的实现：

 # 定义一个栈类

 class Stack():

     # 栈的初始化

     def __init__(self):

         self.items = []

     # 判断栈是否为空,为空返回True

     def isEmpty(self):

         return self.items ==[]

     # 向栈内压入一个元素

     def push(self, item):

         self.items.append(item)

     # 从栈内推出最后一个元素

     def pop(self):

         return self.items.pop()

     # 返回栈顶元素

     def peek(self):

         return self.items[len(self.items)-1]

     # 判断栈的大小

     def size(self):

         return len(self.items)

字符串反转：

 #字符串反转

 def revstring(str):

     s = Stack()

     outputstr = ''

     for i in str:

         s.push(i)

     while not s.isEmpty():

         outputstr += s.pop()

     return outputstr

括号匹配：

 #括号匹配

 def parCheker(str):

     s = Stack()

     balanced = True

     index = 0

     while index<len(str) and balanced:

         str1 = str[index]

         if str1 in '([{':

             s.push(str1)

         else:

             if s.isEmpty():

                 balanced = False

             else:

                 top = s.pop()

                 if not matches(top,str1):

                     balanced = False

         index += 1

     if s.isEmpty() and balanced:

         return True

     else:

         return False

 def matches(open,close):

     opens = '([{'

     closes = ')]}'

     return opens.index(open) == closes.index(close)

十进制转换成二进制：

 #十进制转换为二进制

 def Dec2Bin(num):

     s = Stack()

     while num>0:

         temp = num%2

         s.push(temp)

         num = num // 2

     binString = ''

     while not s.isEmpty():

         binString += str(s.pop())

     return binString

参考：https://github.com/Jack-Lee-Hiter/AlgorithmsByPython/blob/master/Stack.py