Python数据结构之双向链表的定义与使用方法示例

本文实例讲述了Python数据结构之双向链表的定义与使用方法。分享给大家供大家参考，具体如下：

和单链表类似，只不过是增加了一个指向前面一个元素的指针而已。

示意图：

python 实现代码：

#!/usr/bin/python# -*- coding: utf-8 -*-class Node(object):  def __init__(self,val,p=0):    self.data = val    self.next = p    self.prev = pclass LinkList(object):  def __init__(self):    self.head = 0  def __getitem__(self, key):    if self.is_empty():      print 'linklist is empty.'      return    elif key <0 or key > self.getlength():      print 'the given key is error'      return    else:      return self.getitem(key)  def __setitem__(self, key, value):    if self.is_empty():      print 'linklist is empty.'      return    elif key <0 or key > self.getlength():      print 'the given key is error'      return    else:      self.delete(key)      return self.insert(key)  def initlist(self,data):    self.head = Node(data[0])    p = self.head    for i in data[1:]:      node = Node(i)      p.next = node      node.prev = p      p = p.next  def getlength(self):    p = self.head    length = 0    while p!=0:      length+=1      p = p.next    return length  def is_empty(self):    if self.getlength() ==0:      return True    else:      return False  def clear(self):    self.head = 0  def append(self,item):    q = Node(item)    if self.head ==0:      self.head = q    else:      p = self.head      while p.next!=0:        p = p.next      p.next = q      q.prev = p  def getitem(self,index):    if self.is_empty():      print 'Linklist is empty.'      return    j = 0    p = self.head    while p.next!=0 and j <index:      p = p.next      j+=1    if j ==index:      return p.data    else:      print 'target is not exist!'  def insert(self,index,item):    if self.is_empty() or index<0 or index >self.getlength():      print 'Linklist is empty.'      return    if index ==0:      q = Node(item,self.head)      self.head = q    p = self.head    post = self.head    j = 0    while p.next!=0 and j<index:      post = p      p = p.next      j+=1    if index ==j:      q = Node(item,p)      post.next = q      q.prev = post      q.next = p      p.prev = q  def delete(self,index):    if self.is_empty() or index<0 or index >self.getlength():      print 'Linklist is empty.'      return    if index ==0:      q = Node(item,self.head)      self.head = q    p = self.head    post = self.head    j = 0    while p.next!=0 and j<index:      post = p      p = p.next      j+=1    if index ==j:      post.next = p.next      p.next.prev = post  def index(self,value):    if self.is_empty():      print 'Linklist is empty.'      return    p = self.head    i = 0    while p.next!=0 and not p.data ==value:      p = p.next      i+=1    if p.data == value:      return i    else:      return -1l = LinkList()l.initlist([1,2,3,4,5])print "武林站长站测试结果："print l.getitem(4)l.append(6)print l.getitem(5)l.insert(4,40)print l.getitem(3)print l.getitem(4)print l.getitem(5)l.delete(5)print l.getitem(5)l.index(5)