python双向链表和单链表类似，只不过是增加了一个指向前面一个元素的指针,下面的代码实例了python双向链表的方法
示意图：
python双向链表实现代码：
# -*- coding: utf-8 -*- class Node(object): def __init__(self, val, p=0): self.data = val self.next = p self.prev = p class 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 -1 l = LinkList() l.initlist([1, 2, 3, 4, 5]) 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)
输出：
5
6
4
40
5
6