python链式栈，双向链表基础练习代码

 链式栈

class Node:
    def __init__(self, data):
        self.data = data
        self.next = None


class LinkedStack:
    def __init__(self):
        self.top = None  # 初始化时栈顶为空

    # 入栈操作
    def push(self, data):
        new_node = Node(data)  # 创建一个新节点
        new_node.next = self.top  # 新节点指向当前栈顶
        self.top = new_node  # 更新栈顶为新节点

    # 判断栈是否为空
    def is_empty(self):
        return self.top is None

    # 出栈操作
    def pop(self):
        if self.is_empty():
            print('栈为空')
        popped_node = self.top  # 保存当前栈顶节点
        self.top = self.top.next  # 更新栈顶指针
        return popped_node.data  # 返回出栈的节点数据

    # 取栈顶操作
    def peek(self):
        if self.is_empty():
            print('栈为空')
        return self.top.data  # 返回栈顶节点的数据

    # 打印栈
    def show(self):
        current = self.top
        while current:
            print(current.data,end=' ')
            current = current.next
        print()

    #栈大小
    def big(self):
        m=0
        current = self.top
        while current:
            m=m+1
            current = current.next
        print('大小为',m)
l=LinkedStack()
l.push(3)
l.push(4)
l.push(5)
l.push(6)
l.push(7)
l.push(8)
l.show()
l.big()

双向链表

class Node:
    def __init__(self, data):
        self.data = data
        self.next = None
        self.prev = None


class LinklistS:
    def __init__(self, node=None):
        self.size = 0
        self.head = node

    def isEmpty(self):
        return self.size == 0

    def add_tail(self, data):
        node = Node(data)
        if self.isEmpty():
            self.head = node
            node.prev = node
            node.next = node
            self.size += 1
        else:
            p = self.head
            while p.next != self.head:
                p = p.next
            p.next = node
            node.next = self.head
            self.head.prev = node
            self.size += 1

    def show(self):
        if self.isEmpty():
            print("Empty List")
        else:
            p = self.head
            while p.next != self.head:
                print(p.data, end=' ')
                p = p.next
            print(p.data)

    def remove_tail(self):
        if self.isEmpty():
            print("Empty List")
        else:
            if self.size == 1:
                self.head = None
                self.size = 0
            else:
                p = self.head
                while p.next.next != self.head:
                    p = p.next
                p.next = self.head
                self.head.prev = p
                self.size -= 1


l = LinklistS()
l.add_tail(1)
l.add_tail(2)
l.add_tail(3)
l.remove_tail()
l.show()
l.add_tail(4)
l.add_tail(5)
l.add_tail(6)
l.remove_tail()
l.show()