Create and Initialize Doubly Linked List in DSA C - 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 pointer to the next node, and a pointer 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 in C?

A node has: 1) data (the value stored), 2) a pointer to the next node, and 3) a pointer to the previous node.

beginner

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

You create a pointer to the head node and set it to NULL, meaning the list has no nodes yet.

intermediate

Why do we need both next and previous pointers in a doubly linked list?

Next pointer lets us move forward, previous pointer lets us move backward. This makes it easy to traverse the list in both directions.

beginner

Show the C struct definition for a doubly linked list node.

struct Node { int data; struct Node* next; struct Node* prev; };

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

A The previous node in the list

B The next node in the list

C The head of the list

D The last node in the list

The 'prev' pointer points to the previous node, allowing backward traversal.

How do you represent an empty doubly linked list in C?

A Head pointer points to itself

B Head pointer points to a dummy node

C Head pointer set to NULL

D Head pointer points to zero

An empty list has the head pointer set to NULL, meaning no nodes exist.

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

A Data field

B Pointer to head node

C Pointer to next node

D Pointer to previous node

Nodes do not store a pointer to the head node; only next and prev pointers.

What is the main advantage of a doubly linked list over a singly linked list?

A Can traverse both forward and backward

B Uses less memory

C Simpler to implement

D Faster insertion at head only

Doubly linked lists allow traversal in both directions due to prev pointers.

In C, how do you declare a pointer to a doubly linked list node?

A struct Node ptr;

B Node ptr;

C int* ptr;

D struct Node* ptr;

You declare a pointer to struct Node using 'struct Node* ptr;'.

Explain how to create and initialize an empty doubly linked list in C.

Think about the node structure and how to represent no nodes.

Describe the role of next and prev pointers in a doubly linked list node.

Focus on how these pointers help move through the list.