python-单链表的实现

  #!/usr/bin/python

 class Node(object):
     def __init__(self,value,next=None):
         self.value,self.next=value,next

 class Linklist(object):
     def __init__(self):
         self.head=None
     def initlist(self,data):
         self.head=Node(0)
         p=self.head

         for i in data:
             node=Node(i)
             p.next=node
             p=p.next

     def show(self):
         p=self.head.next
         while p!=None:
             print p.value
             p=p.next
     def getlength(self):
         p=self.head
         length=0

         while p.next !=None:
             length+=1
             p=p.next
         return length

     def insert(self,index,value):
         if index<0 or index>self.getlength():
             print "Index is Error!"
             return
         p=self.head
         j=0
         while p.next !=None and j < index:
             p=p.next
             j+=1
         node=Node(value,p.next)
         p.next=node

     def remove(self,index):
         if index<0 or index > self.getlength():
             print "Index is Error!"
             return 

         p=self.head
         j=0
         while p.next !=None and j<index:
             p=p.next
             j+=1
         next=p.next.next

     def checkin(self,value):
         p=self.head
         flag=-1
         while p.next != None:
             if p.next.value==value:
                 flag=1
                 return flag
             p=p.next
         return flag  

     def replace(self,index,value):
         p=self.head.next
         i=0
         while i<index:
             p=p.next
             i+=1
         p.value=value

     def getitem(self,index):
         p=self.head.next
         j=0
         while p!=None and j<index:
             j+=1
             p=p.next
         return p.value

     def is_empty(self):
         if self.getlength()==0:
             return True
         else:
             return False

     def __getitem__(self,key):
         if self.is_empty() or key>=self.getlength():
             print "Index is Error!"
             return
         else:
             return self.getitem(key)
     def __setitem__(self,key,value):
         if self.is_empty() or key>=self.getlength():
             print "Index is Error!"
             return
         else:
             return self.replace(key,value)