---
title: "Significance of circular linked list"
subject: "Data Structure and Algorithm"
chapter: 4
key: "semester_4/data_structure_and_algorithm:circular-linked-list-significance"
source: https://www.bctengineer.com/q/semester_4/data_structure_and_algorithm/circular-linked-list-significance
site: BCT Engineering
---

# Significance of circular linked list

Data Structure and Algorithm · Chapter 4: Linked lists

- Asked in: 2071 Magh, 5 marks
- Video: [Circular Linked List Tutorial - Why Use a Circular List?](https://www.youtube.com/watch?v=gztwNv4o_9E) — Tech With Tim
- 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/circular-linked-list-significance
- Whole chapter: https://www.bctengineer.com/md/semester_4/data_structure_and_algorithm/chapter-4

## Question

Mention the significance of circular linked list with suitable example.

## Short answer

In a circular linked list the last node points to the first, allowing traversal from any node to all others, no NULL. With only a rear pointer, insertion at both ends is O(1). It naturally models cyclic processes like round-robin CPU scheduling, where after the last process the scheduler returns to the first automatically.

## Answer

In a **circular linked list** the `next` pointer of the last node points to the first node, not to NULL. There is no NULL anywhere in the list.

```text
 last
  |
  v
 [10|*]->[20|*]->[30|*]--+
   ^                      |
   +----------------------+
```

#### Significance (uses)
1. **Any node can be reached from any other node**: starting from any node we can traverse the whole list, which is not possible in an ordinary (linear) singly linked list.
2. **Easy access to both ends with one pointer**: if we keep a pointer `last` to the last node, then `last->next` is the first node. Insertion at the front or the end is O(1).
3. **Natural for cyclic problems**: round-robin CPU scheduling (the scheduler moves to the next process and returns to the first after the last), Josephus problem, multiplayer turn-taking, music playlists on repeat, buffers.
4. **Efficient circular queue**: a queue with `rear` only; enqueue after `rear`, dequeue `rear->next`, with no wasted space.
5. **No NULL checks for the end**: the stop condition is returning to the start node.

#### Example: round-robin
Processes P1, P2, P3 in a circular list with time slice 4 ms: CPU serves P1, P2, P3, then comes back to P1 automatically by following `next`. A finished process is simply deleted from the ring.

Traversal must stop when the start node is met again, otherwise it loops forever:
```c
p = last->next;           /* first node */
do { printf("%d ", p->info); p = p->next; } while (p != last->next);
```

## Check yourself

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

1. What is the defining feature of a circular linked list?
   A. The last node's next points to the first node, so there is no NULL
   B. It has two pointers per node
   C. It holds a count in a header
   D. It can be traversed only once
   Answer: A. The ring structure removes NULL from the list. (Key point: Defining feature)

2. If we keep a pointer last to the last node, how do we reach the first node?
   A. last->prev
   B. last->next
   C. start->last
   D. It requires traversal
   Answer: B. The next of the last node is the first, so both ends are O(1) accessible. (Key point: One pointer to both ends)

3. Which problem is naturally modelled by a circular list?
   A. Binary search
   B. Stack evaluation of postfix
   C. Round-robin CPU scheduling
   D. Sorting by merge
   Answer: C. The scheduler cycles through processes and returns to the first after the last. (Key point: Applications)

4. How must traversal of a circular list stop?
   A. When next is NULL
   B. After n+1 steps always
   C. When info is 0
   D. When the start node is met again
   Answer: D. There is no NULL, so otherwise it would loop forever. (Key point: Traversal stop)

## Related in Data Structure and Algorithm

- [Circular queue using linked list](https://www.bctengineer.com/question.md?key=semester_4%2Fdata_structure_and_algorithm%3Acircular-queue-linked-list) — Data Structure and Algorithm, chapter 4
- [Doubly linked list and its merits](https://www.bctengineer.com/question.md?key=semester_4%2Fdata_structure_and_algorithm%3Adoubly-linked-define-merits) — Data Structure and Algorithm, chapter 4

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