Create Double Links - codepath/compsci_guides GitHub Wiki

Unit 5 Session 2 (Click for link to problem statements)

U-nderstand

Understand what the interviewer is asking for by using test cases and questions about the problem.

• How does the constructor need to be structured to support both forward and backward traversal in a doubly linked list?
  • The constructor must initialize each node with next and prev attributes, allowing links to both the subsequent and preceding nodes.

P-lan

Plan the solution with appropriate visualizations and pseudocode.

General Idea: Modify the Node class constructor to include both next and prev parameters, initializing them to None by default. This setup will allow each node to potentially link to both the next and previous nodes in a doubly linked list.

1) Define the class `Node` with the constructor accepting `value`, `next`, and `prev` parameters.
2) Initialize the `value` attribute to hold the node's data.
3) Set the `next` attribute to point to the next node in the list, defaulting to `None`.
4) Set the `prev` attribute to reference the previous node in the list, also defaulting to `None`.

⚠️ Common Mistakes

• Omitting the initialization of the prev attribute, which is essential for the backward linkage in a doubly linked list.
• Failing to correctly handle default parameters, potentially leading to nodes that are not correctly linked.

I-mplement

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