棧Stack

 

class Stack:
    def __init__(self):
        self.items=[]
    def isEmpty(self):
        return self.items==[]
    def push(self,item):
        #添加元素進站
        self.items.append(item)
    def peek(self):
        #打印棧頂元素
        return self.items[len(self.items)-1]
    def pop(self):
        #從棧頂取出元素
        return self.items.pop()
    def size(self):
        #返回棧中元素的個數
        return len(self.items)

棧的另外一種實現是把列表的首端（index=0）做爲棧頂同樣能夠實現Stack

class Stack:
    def __init__(self):
        self.items=[]
    def isEmpty(self):
        return self.items==[]
    def push(self,item):
        #添加元素進站
        self.items.insert(0,item)
    def peek(self):
        #打印棧頂元素
        return self.items[0]
    def pop(self):
        #從棧頂取出元素
        return self.items.pop(0)
    def size(self):
        #返回棧中元素的個數
        return len(self.items)

def parChecker(symbolString):
    #單一括號匹配函數
    s=Stack()
    balanced=True
    index=0
    #判斷索引值和字符串的大小 ，當前是否匹配
    while index<len(symbolString) and balanced:
        symbol=symbolString[index]
        if symbol =="(":
            s.push(symbol)
        else:
            if s.isEmpty():
                balanced=False
            else:
                s.pop()
        index=index+1
    if balanced and s.isEmpty():
        return True
    else:
        return False

print(parChecker("(()))"))

def TYparChecker(symbolString):
    #多種類型括號匹配方法
    s=Stack()
    balanced=True
    index=0
    while index<len(symbolString) and balanced:
        symbol=symbolString[index]
        if symbol in '([{':
            s.push(symbol)
        else:
            if s.isEmpty():
                balanced= False
            else:
                top=s.pop()
                if not matchs(top,symbol):
                    balanced=False
        index=index+1
    if balanced and s.isEmpty():
        return True
    else:
        return False

def matchs(open,close):
    opens='([{'
    closers=')]}'
    return opens.index(open)==closers.index(close)print(TYparChecker("{{[()]}"))