The implementation of single chain table of python data structure

Reprinted from https://www.cnblogs.com/yupeng/p/3413763.html

Definition of linked list:

Linked list is a data structure composed of a group of data elements called nodes. Each node contains the information of the node itself and the address to the next node. Because each node contains address information that can be linked, the whole node sequence can be accessed with one variable. That is to say, the node contains two parts of information: one is used to store the value of data element, which is called information domain; the other is used to store the pointer of the next data element address, which is called pointer domain. The address of the first node in the list is stored in a separate node, which is called the head node or the head node. The last node in the list has no successor element, and its pointer field is empty.   

As shown in the figure below:

 

Structure of single chain table:

Schematic diagram of insertion and deletion of single chain table:

#!/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)

Result:

5
6
4
40
5
6

Tags: Python

Posted on Sun, 09 Feb 2020 15:29:23 -0500 by luke101