FAQ: Doubly Linked Lists: Python - Adding to the Head

Frequently Asked Questions Python FAQ
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This community-built FAQ covers the “Adding to the Head” exercise from the lesson “Doubly Linked Lists: Python”.

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This exercise can be found in the following Codecademy content:

Pass the Technical Interview with Python

FAQs on the exercise Adding to the Head

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3

In the below code, how is it changing the value of <self.head_node.prev_node> by chaging value of <current_head>, which was assigned by <self.head_node>. The question is, how is it possible to change value of variable A by changing variable B?
current_head = self.head_node
current_head.set_prev_node(new_head)

4

I rather use directly <self.head_node>.

self.head_node.set_prev_node(new_head)

Creating temporal variable <current_head> is confusing for people new to python.

5

There’s a bug in Instruction 2

if current_head != None: works

but

if current_head: doesn’t works

(It says that check if current_head is not None)

1 Like
6

I’m a little bit confused on why we’re making the tail equal to the new head, shouldn’t the tail be the previous head (current_head)

7

If there is no head node (meaning the .head_node is None), then there wouldn’t be a previous head node.