Insert element at the tail of a linked list, Python 3 hackerrank

Question

Python 3 Problem

I need to know how to solve the problem, here is my code (obviously incorrect) and I also attached the link of the hackerrank challenge. All of the previous answers is in older python and the exercise itself has considerably changed. All you have to do is insert data at the tail of the linked list. Thank you very much and have a good day.

def insertNodeAtTail(head, data):
    if head == None:
        head.data = data
        return head
    else: 
        while head:
            head = head.next
        head.data = data
        return head

Answer 1

Found the answer

def insertNodeAtTail(head, data):
    if head is None:
            return SinglyLinkedListNode(data)
    pnt = head
    while pnt.next:
            pnt = pnt.next
    pnt.next = SinglyLinkedListNode(data)
    return head

Answer 2

Well, right off the bat, I can see a big problem. You check for head == None , and if that is True , then you proceed to try to set the data attribute in an object that doesn't exist...in None . Also, you should be using if head is None . If that succeeds, what you probably want to do is create a new Node object, set its data attribute to the incoming data, and set head to point to that new node.

You have a similar issue with the other half of your code. Your code doesn't add a Node in the case of an existing list either...it just changes the data that the last Node in the list is pointing to. Here, you want to create a Node containing your passed in data, and point node.next to it.

I don't know the details of how you create a node, but here's about what your code should look like:

def insertNodeAtTail(head, data):
    if head is None:
        head = Node(data)
        return head
    else:
        node = head
        while node.next:
            node = node.next
        node.next = Node(data)
        return head

It is assumed that Node() sets its next attribute to None and sets its data attribute to the passed in data.