---
title: "Singly vs doubly linked list"
subject: "Data Structure and Algorithm"
chapter: 4
key: "semester_4/data_structure_and_algorithm:singly-vs-doubly-linked"
source: https://www.bctengineer.com/q/semester_4/data_structure_and_algorithm/singly-vs-doubly-linked
site: BCT Engineering
---

# Singly vs doubly linked list

Data Structure and Algorithm · Chapter 4: Linked lists

- Asked in: 2068 Bhadra, 2 marks
- Video: [Singly vs Doubly Linked List 🔥 | Clear Difference Explained with Examples!](https://www.youtube.com/watch?v=DsYGlKSC3wo) — Kailash Joshi Tutorials
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_4/data_structure_and_algorithm/singly-vs-doubly-linked
- Whole chapter: https://www.bctengineer.com/md/semester_4/data_structure_and_algorithm/chapter-4

## Question

Differentiate singly linked list from doubly linked list.

## Short answer

Singly linked list has one next pointer per node, allowing only forward traversal; deletion requires finding the predecessor. Douly linked list has prev and next pointers, enabling bidirectional traversal and direct node deletion using the prev pointer, but uses more memory.

## Answer

| Basis | Singly linked list | Doubly linked list |
|---|---|---|
| Pointers in a node | One (`next`) | Two (`prev` and `next`) |
| Traversal | Forward only | Forward and backward |
| Memory | Less | More |
| Node deletion | Needs previous node, O(n) search | Direct using `prev` |
| Pointer changes | Fewer | More |

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. How many pointers per node in singly vs doubly list?
   A. Two vs one
   B. One vs three
   C. One vs two
   D. Same
   Answer: C. Doubly has next and prev. (Key point: Pointers)

2. Which statement is correct?
   A. Singly both directions
   B. Doubly forward only
   C. Both forward only
   D. Singly is forward only, doubly both directions
   Answer: D. prev enables backward movement. (Key point: Traversal)

3. Why is node deletion simpler in a doubly list?
   A. prev gives the previous node directly
   B. No pointers change
   C. Memory is contiguous
   D. Uses fewer pointers
   Answer: A. A singly list needs an O(n) search for the predecessor. (Key point: Deletion)

## Related in Data Structure and Algorithm

- [Doubly vs singly linked list](https://www.bctengineer.com/question.md?key=semester_4%2Fdata_structure_and_algorithm%3Adoubly-vs-singly-linked) — Data Structure and Algorithm, chapter 4, asked 2×
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- [Insert and delete kth node in doubly linked list](https://www.bctengineer.com/question.md?key=semester_4%2Fdata_structure_and_algorithm%3Adoubly-insert-delete-kth) — Data Structure and Algorithm, chapter 4, asked 2×
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