Making a function to clone a linked list without using the copy function

Question

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

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

    # find a node which contains the data matching the input value 
    def findNode(self, value): 
        curr = self.head
        while curr:
            if curr.data == value:
                return curr
            curr = curr.next 
        return curr 

    # add a new node as the first node      
    def addNode(self, data):
        newNode = Node(data)  # create the new node 
        newNode.next = self.head 
        self.head = newNode
        self.size+=1

    # print the data in all the nodes 
    def printNode(self):
        listprint = [] 
        curr = self.head
        while curr:
            listprint.append(curr.data)
            curr = curr.next 
        print(listprint) 

#what i am trying to make
def duplicateLL(original):
    newlist = LinkedList()
    curr = original
    if not curr:
        return 
    while curr != None:
        newlist.addNode(curr)
        curr = curr.next 
    return newlist

#to test if function works
LLA = LinkedList()
for n in range(1,5):
    LLA.addNode(n)
LLB = duplicateLL(LLA)
# modify LLA
curr = LLA.head
for n in range(LLA.size):
    curr.data += 10
    curr = curr.next
LLA.printNode()
LLB.printNode()

# driver code will be executed if this file is executed directly
# driver code will not be executed if this file is imported into another file 
if __name__ == "__main__":   
    mylinkedlist = LinkedList()
    
    for i in range(5):
        mylinkedlist.addNode(2*i)
    
    mylinkedlist.printNode()  

I am trying to make a function duplicateLL, which is outside of the linked list class. Function duplicateLL is supposed to clone a linked list without using the built in copy function.

**** Note that I can only edit the function duplicateLL.***

The code prompts out: 'LinkedList' object has no attribute 'next'.

What am I doing wrong?

The outputs should be:

[14, 13, 12, 11]

[4, 3, 2, 1]

[8, 6, 4, 2, 0]

Answer 1

There was two problem for the duplicateLL function.

First, you tried to search through LinkedList which has no next attribute. Therefore, you need to use Node to travel through each element, so I assigned Node attribute to curr variable in duplicateLL function.

Second, you need to add the data of the node with the addNode function. I changed that part as well.

Here is the code:

def duplicateLL(original : LinkedList):
    newlist = LinkedList()
    curr = original.head
    if not curr:
        return 
    while curr != None:
        newlist.addNode(curr.data)
        curr = curr.next 
    return newlist.reverse()