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