链表的定义：
链表(linked list)是由一组被称为结点的数据元素组成的数据结构，每个结点都包含结点本身的信息和指向下一个结点的地址。由于每个结点都包含了可以链接起来的地址 信息，所以用一个变量就能够访问整个结点序列。也就是说，结点包含两部分信息：一部分用于存储数据元素的值，称为信息域；另一部分用于存储下一个数据元素 地址的指针，称为指针域。链表中的第一个结点的地址存储在一个单独的结点中，称为头结点或首结点。链表中的最后一个结点没有后继元素，其指针域为空。
#!/usr/bin/python
# -*- coding: utf-8 -*- class Node(object):
def __init__(self,val,p=0):
self.data = val
self.next = 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
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 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.next = p 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 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)