Traversal Forward and Backward in DSA Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does forward traversal mean in a linked list?

Forward traversal means moving from the first node to the last node by following the next links one by one.

beginner

What is backward traversal in a doubly linked list?

Backward traversal means moving from the last node to the first node by following the previous links one by one.

beginner

Why can't we do backward traversal in a singly linked list?

Because singly linked lists only have links to the next node, not to the previous one, so we cannot move backward easily.

beginner

In a doubly linked list, which pointers are used for forward and backward traversal?

The 'next' pointer is used for forward traversal, and the 'prev' pointer is used for backward traversal.

beginner

What is the output after forward traversal of this doubly linked list: 1 <-> 2 <-> 3 <-> null?

The output is: 1 -> 2 -> 3 -> null

Which traversal is possible in a singly linked list?

A No traversal possible

B Backward traversal only

C Forward traversal only

D Both forward and backward traversal

Singly linked lists have links only to the next node, so only forward traversal is possible.

In a doubly linked list, what does the 'prev' pointer do?

A Points to the previous node

B Points to the head node

C Points to the next node

D Points to the tail node

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

What is the first step in forward traversal of a linked list?

A Start from the tail node

B Start from the head node

C Start from the middle node

D Start from any random node

Forward traversal always starts from the head node and moves forward.

Which data structure allows easy traversal both forward and backward?

A Doubly linked list

B Singly linked list

C Stack

D Queue

Doubly linked lists have pointers to both next and previous nodes, allowing traversal in both directions.

What will be the output of backward traversal of this doubly linked list: 1 <-> 2 <-> 3 <-> null?

A 1 -> 2 -> 3 -> null

B 3 -> null -> 2 -> 1

C null -> 1 -> 2 -> 3

D 3 -> 2 -> 1 -> null

Backward traversal starts from the last node and moves to the first, so output is 3 -> 2 -> 1 -> null.

Explain how forward and backward traversal work in a doubly linked list.

Think about the pointers that connect nodes in both directions.

Why is backward traversal not possible in a singly linked list? How does a doubly linked list solve this?

Focus on the difference in node connections.