python棧--字符串反轉，括號匹配

棧的實現：

# 定義一個棧類
class Stack():
    # 棧的初始化
    def __init__(self):
        self.items = []
    # 判斷棧是否為空,為空返回True
    def isEmpty(self):
        return self.items ==[]
    # 向棧內壓入一個元素
    def push(self, item):
        self.items.append(item)
    # 從棧內推出最后一個元素
    def pop(self):
        return self.items.pop()
    # 返回棧頂元素
    def peek(self):
        return self.items[len(self.items)-1]
    # 判斷棧的大小
    def size(self):
        return len(self.items)

 

字符串反轉：

#字符串反轉
def revstring(str):
    s = Stack()
    outputstr = ''

    for i in str:
        s.push(i)
    while not s.isEmpty():
        outputstr += s.pop()

    return outputstr

 

括號匹配：

#括號匹配
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)

 

十進制轉換成二進制：

#十進制轉換為二進制
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

 

 

 

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