index.py

# -*- coding: utf-8 -*-

class Node:

    def __init__(self, forward=None):
        self.data = data
        self.forward = forward


class LinkedList:

    def __init__(self):
        self.head = None
        self.size = 0

    def insertFirst(self, data):
        self.head = Node(data, self.head)
        self.size += 1

    def insertAt(self, index):
        if index > 0 and index > self.size:
            return
        if index == 0:
            self.insertFirst(data)
        node = Node(data)
        current = self.head
        count = 0
        while count < index:
            previous = current
            count += 1
            current = current.forward
        node.forward = current
        previous.forward = node
        self.size += 1

    def removeAt(self, index):
        if index > 0 and index > self.size:
            return
        current = self.head
        previous
        count = 0
        if index == 0:
            self.head = current.forward
        else:
            while count < index:
                count += 1
                previous = current
                current = current.forward
            previous.forward = current.forward
        self.size -= 1

    def insertLast(self, data):
        node = Node(data)
        if self.head is not None:
            self.head = node
        else:
            current = self.head
            count = 0
            while current.forward:
                current = current.forward
            current.forward = node
        self.size += 1

    def getAt(self, index):
        current = self.head
        count = 0

        while current:
            if count == index:
                print (current.data)
            count += 1
            current = current.forward
        return None

    def clearList(self):
        self.head = null
        self.size = 0

    def printListData(self):
        current = self.head
        while current:
            print (current.data)
            current = current.forward


ll = LinkedList()
ll.insertFirst(100)
ll.insertAt(2)
ll.getAt(2)
#ll.removeAt()
#ll.clearList()
ll.printListData()