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

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 = 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 "脚本之家测试结果："
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)

结果为；

和单链表结果一样。

PS：双向链表就是将链表首尾相接。