棧的實現

class Stack(object):
    """棧"""
    def __init__(self):
        self.__list = []

    def push(self, item):
        """新增一個新的元素item到棧頂"""
        self.__list.append(item)

    def pop(self):
        """彈出棧頂元素"""
        return self.__list.pop()

    def peek(self):
        """返回棧頂元素"""
        if self.__list:
            return self.__list[-1]
        else:
            return None

    def is_empty(self):
        """判斷棧是否為空"""
        return self.__list == []
        # return not self.__list

    def size(self):
        """返回棧的元素個數"""
        return len(self.__list)


if __name__ == "__main__":
    s = Stack()
    s.push(1)
    s.push(2)
    s.push(3)
    s.push(4)
    print(s.pop())
    print(s.pop())
    print(s.pop())
    print(s.pop())
 

佇列的實現

class Queue(object):
    """佇列"""
    def __init__(self):
        self.__list = []

    def enqueue(self, item):
        """往佇列中新增一個item元素"""
        self.__list.append(item)

    def dequeue(self):
        """從佇列頭部刪除一個元素"""
        return self.__list.pop(0)

    def is_empty(self):
        """判斷一個佇列是否為空"""
        return self.__list == []

    def size(self):
        """返回佇列的大小"""
        return len(self.__list)


if __name__ == "__main__":
    s = Queue()
    s.enqueue(1)
    s.enqueue(2)
    s.enqueue(3)
    s.enqueue(4)
    print(s.dequeue())
    print(s.dequeue())
    print(s.dequeue())
    print(s.dequeue())