双向链表的原理与实践

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说明：

本内容是学习：编程必备基础知识-计算机组成原理+操作系统+计算机网络-慕课网实战

所记学习笔记，仅供学习参考

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如下开始，笔记正文：

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @Time : 2022/6/8 23:35
# @Author : chaitc
# @File : DoubleLinkTable.py
class Node:
    def __init__(self,key,value):
        self.key = key
        self.value = value
        self.prev =None
        self.next =None

    def __str__(self):
        val = '{%d %d}' %(self.key,self.value)
        return val

    def __repr__(self):
        val = '{%d %d}' %(self.key,self.value)

class DoubleLinkList:
    def __init__(self,capacity=0xffff):
        self.capacity = capacity
        self.head = None
        self.tail = None
        self.size = 0

    # 从头部添加节点
    def __add_head(self,node):
        if not self.head:
            self.head = node
            self.tail = node
            self.head.prev = None
            self.head.next = None
        else:
            node.next = self.head
            self.head.prev = node
            self.head = node
            self.head.prev = None

        self.size += 1
        return node

    # 从尾部添加节点
    def __add_tail(self,node):
        if not self.tail:
            self.tail = node
            self.head = node
            self.tail.prev = None
            self.tail.next = None
        else:
            node.prev = self.tail
            self.tail.next = node
            self.tail = node
            self.tail.next = None

        self.size += 1
        return node

    # 从尾部删除
    def __del_tail(self):
        if not self.tail:
            return
        node = self.tail
        if self.head:
            self.tail = node.prev
            self.tail.next = None
        else:
            self.head = self.tail = None
        self.size -= 1
        return node

    # 从头部删除
    def __del_head(self):
        if not self.head:
            return
        node = self.head
        if node.next:
            self.head = node.next
            self.head.prev = None
        else:
            self.tail = self.head = None
        self.size -= 1
        return node

    # 任意节点删除
    def __remove(self, node):
        # 如果node = Node，默认删除尾部节点
        if not node:
            node = self.tail
        if node == self.tail:
            self.__del_tail()
        elif node == self.head:
            self.__del_head()
        else:
            node.next.prev = node.prev
            node.prev.next = node.next
            self.size -= 1
        return node

    # 弹出头部节点
    def pop(self):
        return self.__del_head()

    # 添加节点
    def append(self,node):
        return self.__add_tail(node)

    # 往头部添加节点
    def append_front(self,node):
        return self.__add_head(node)

    # 删除节点
    def remove(self,node=None):
        return self.__remove(node)

    # 打印链表
    def print(self):
        p = self.head
        line = ''
        while p:
            line += '%s' % p
            p = p.next
            if p:
                line += '<===>'
        print(line)

if __name__ == "__main__":
    l = DoubleLinkList(10)
    nodes = []
    for i in range(10):
        node = Node(i, i)
        nodes.append(node)

    l.append(nodes[0])
    l.print()
    l.append(nodes[1])
    l.print()
    l.pop()
    l.print()
    l.append(nodes[2])
    l.print()
    l.append_front(nodes[3])
    l.print()
    l.append(nodes[4])
    l.print()
    l.remove(nodes[2])
    l.print()
    l.remove()
    l.print()