python创建双链表

学习关于python创建双向链表，编写代码以作记录

 

 

 

# -*- coding: utf-8 -*-

class Node(object):
    """节点"""
    def __init__(self, elem):
        self.elem = elem
        self.next = None
        self.prev=None


class doubleLinkList(object):
    '''双向链表'''

    def __init__(self, Node=None):
        self.__head = Node

    def is_empty(self):
        """链表是否为空"""
        return self.__head == None

    def length(self):
        """链表长度"""
        # cur游标，用来移动遍历节点
        cur = self.__head
        # count记录数量
        count = 0
        while cur != None:
            count += 1
            cur = cur.next
        return count

    def travel(self):
        """遍历整个链表"""
        cur = self.__head
        while cur != None:
            print(cur.elem, end=" ")
            cur = cur.next
        print("")

    def add(self, item):
        """链表头部添加元素，头插法"""
        node = Node(item)
        node.next = self.__head
        self.__head.prev=node
        self.__head = node

    def append(self, item):
        """链表尾部添加元素, 尾插法"""
        node = Node(item)
        if self.is_empty():
            #node.next=self.__head
            self.__head = node


        else:
            cur = self.__head
            while cur.next != None:
                cur = cur.next
            node.next=cur.next
            node.prev=cur
            node.prev.next=node


    def insert(self, pos, item):
        """指定位置添加元素
        :param  pos 从0开始
        """
        node=Node(item)
        if pos <= 0:
            self.add(item)
        elif pos > (self.length()-1):
            self.append(item)
        else:
            count = 0
            cur=self.__head
            while count < pos:
                count += 1
                cur=cur.next

            node.next=cur
            node.prev=cur.prev
            cur.prev.next=node
            cur.prev=node


    def remove(self, item):
        """删除节点"""
        cur = self.__head
        while cur != None:
            if cur.elem == item:
                # 先判断此结点是否是头节点
                # 头节点
                if cur == self.__head:
                    self.__head = cur.next
                    if cur.next:
                        #判断是否只有一个节点
                        cur.next.prev=None
                else:
                    cur.prev.next = cur.next
                    if cur.next:
                        cur.next.prev = cur.prev

                break
            else:
                pre = cur
                cur = cur.next

    def search(self, item):
        """查找节点是否存在"""
        cur = self.__head
        while cur != None:
            if cur.elem == item:
                return True
            else:
                cur = cur.next
        return False



if __name__ == "__main__":
    ll = doubleLinkList()
    print(ll.is_empty())
    print(ll.length())

    ll.append(1)
    print(ll.is_empty())
    print(ll.length())


    ll.append(2)
    ll.add(8)
    ll.append(3)
    ll.add(4)
    ll.append(5)
    ll.append(6)

    ll.insert(-1, 9) 
    ll.travel()
    ll.insert(3, 100) 
    ll.travel()
    ll.insert(10, 200) 
    ll.travel()
    ll.remove(100)
    ll.travel()
    ll.remove(9)
    ll.travel()
    ll.remove(200)
    ll.travel()
    print(ll.search(8))


运行结果：

 

学习 参考：

https://www.bilibili.com/video/BV18W411T7Vv?p=16