python实现数据结构中双向循环链表操作

python实现数据结构中双向循环链表操作

    看此博客之前建议先看看B站的视频 python数据结构与算法系列课程，该课程中未实现双向循环链表的操作，所以我按照该视频的链表思路实现了双向循环链表的操作，欢迎大家阅读与交流，如有侵权，请联系博主！
下面附上代码：

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


class DoubleCycleLinkList:
    def __init__(self, node=None):
        self.__head = node

    def is_empty(self):
        """判空"""
        if self.__head is None:
            return True
        return False

    def length(self):
        """链表长度"""
        if self.is_empty():
            return 0
        cur = self.__head
        count = 1
        while cur.next is not self.__head:
            count += 1
            cur = cur.next
        return count

    def travel(self):
        """遍历链表"""
        if self.is_empty():
            return
        cur = self.__head
        while cur.next is not self.__head:
            print(cur.elem, end=" ")
            cur = cur.next
        print(cur.elem, end=" ")
        print("")

    def add(self, elem):
        """头插法"""
        node = Node(elem)
        if self.is_empty():
            self.__head = node
            node.prev = node
            node.next = node
        else:
            self.__head.prev.next = node
            node.prev = self.__head.prev
            node.next = self.__head
            self.__head.prev = node
            self.__head = node

    def append(self, elem):
        """尾插法"""
        node = Node(elem)
        if self.is_empty():
            self.__head = node
            node.prev = node
            node.next = node
        else:
            node.next = self.__head
            node.prev = self.__head.prev
            self.__head.prev.next = node
            self.__head.prev = node

    def insert(self, pos, elem):
        """任一位置（pos）插入， 下标从0数起"""
        if pos <= 0:
            self.add(elem)
        elif pos > (self.length() - 1):
            self.append(elem)
        else:
            count = 0
            cur = self.__head
            node = Node(elem)
            while count < (pos - 1):
                count += 1
                cur = cur.next
            node.next = cur.next
            node.prev = cur
            node.next.prev = node
            cur.next = node

    def remove(self, elem):
        """删除某一节点，若有多个符合条件的节点，删除第一个即可"""
        if self.is_empty():
            return
        cur = self.__head
        while cur.next is not self.__head:
            if cur.elem == elem:
                if cur is self.__head:
                    self.__head = cur.next
                    cur.prev.next = cur.next
                    cur.next.prev = cur.prev
                else:
                    cur.prev.next = cur.next
                    cur.next.prev = cur.prev
                break
            cur = cur.next
        if cur.elem == elem:
            cur.prev.next = self.__head
            self.head = cur.prev

    def search(self, elem):
        """查找某一个节点"""
        if self.is_empty():
            return False
        cur = self.__head
        while cur.next is not self.__head:
            if cur.elem == elem:
                return True
            cur = cur.next
        # while中处理不到尾节点，所以进行最后尾节点的判断
        if cur.elem == elem:
            return True
        return False