Create and Initialize Doubly Linked List in DSA Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a doubly linked list?

A doubly linked list is a chain of nodes where each node has three parts: data, a link to the next node, and a link to the previous node. This allows moving forward and backward through the list.

beginner

What are the main parts of a node in a doubly linked list?

Each node has: <br>1. Data (the value stored)<br>2. Next pointer (link to the next node)<br>3. Previous pointer (link to the previous node)

beginner

How do you initialize an empty doubly linked list in Python?

You create a class for the list with a head pointer set to None, meaning the list starts empty with no nodes.

beginner

Why does a doubly linked list have both next and previous pointers?

Having both pointers allows you to move forward and backward through the list easily, unlike a singly linked list which only moves forward.

beginner

What is the first step when creating a doubly linked list?

Define a Node class with data, next, and previous pointers, then create a DoublyLinkedList class with a head pointer set to None.

What does the 'previous' pointer in a doubly linked list node point to?

A The next node in the list

B The tail of the list

C The previous node in the list

D The head of the list

The 'previous' pointer points to the node before the current one, allowing backward traversal.

How do you represent an empty doubly linked list?

A Head points to a node with data 0

B Head points to itself

C Head points to tail

D Head is None

An empty list has no nodes, so the head pointer is set to None.

Which of these is NOT part of a doubly linked list node?

A Random pointer

B Next pointer

C Previous pointer

D Data

A standard doubly linked list node has data, next, and previous pointers. A random pointer is not standard.

What advantage does a doubly linked list have over a singly linked list?

A Can be traversed backward

B Uses less memory

C Faster insertion at head

D Simpler to implement

Doubly linked lists allow traversal in both directions because of the previous pointer.

When initializing a doubly linked list, what is the initial value of the head pointer?

A 0

B None

C A new node

D Tail node

The head pointer is set to None to indicate the list is empty.

Explain how to create and initialize a doubly linked list from scratch.

Think about what each node needs and how the list starts empty.

Describe the structure of a node in a doubly linked list and why it has two pointers.

Focus on the purpose of each pointer.