20 Circular Linked List Interview Questions and Answers

A Circular Linked List is a data structure that allows for efficient traversal of a sequence of items. When interviewing for a position that involves data structures, it is likely that you will be asked questions about Circular Linked Lists. Answering these questions correctly can help you demonstrate your understanding of the topic and land the job. In this article, we discuss the most common Circular Linked List interview questions and how you should answer them.

Circular Linked List Interview Questions and Answers

Here are 20 commonly asked Circular Linked List interview questions and answers to prepare you for your interview:

1. What are circular linked lists?

A circular linked list is a type of linked list where the last node in the list points back to the first node in the list. This creates a loop or cycle in the list. Circular linked lists are often used in applications where data needs to be processed in a continuous loop, such as in a video game or music player.

2. How do you insert a new node at the front of a circular linked list?

You would insert the new node in between the head node and the node after the head node.

3. How do you delete an existing node in a circular linked list?

You would need to find the node before the one you want to delete, and then change its next pointer to point to the node after the one you want to delete. Then, you can simply delete the node you wanted to delete without having to worry about any pointers becoming orphaned.

4. Can you explain how to traverse a circular linked list?

To traverse a circular linked list, you would start at the head of the list and follow the links until you reach the head again. This will ensure that you visit every node in the list.

5. Is it possible to create a circular doubly-linked list from a normal doubly-linked list? If yes, then how?

Yes, it is possible to create a circular doubly-linked list from a normal doubly-linked list. To do so, you would need to change the pointers of the last node in the list to point back to the first node in the list. This would then create a loop, making the list circular.

6. Are there any advantages or disadvantages associated with circular doubly-linked lists over regular doubly-linked lists?

One advantage of a circular doubly-linked list is that it can be easier to implement certain algorithms with them. For example, it is easier to traverse a circular doubly-linked list in both directions than it is a regular doubly-linked list. However, one disadvantage of a circular doubly-linked list is that it can be more difficult to keep track of the head and tail nodes, since there is no beginning or end to the list.

7. Is it possible to convert a singly-linked list into a circular singly-linked list? If yes, then how?

Yes, it is possible to convert a singly-linked list into a circular singly-linked list. To do so, you simply need to set the next pointer of the last node in the list to point back to the first node in the list. This will create a circular loop that can be traversed in either direction.

8. Is it possible to move all even nodes after odd nodes in a given linked list? If yes, then how?

Yes, it is possible to move all even nodes after odd nodes in a given linked list. This can be accomplished by traversing the linked list and keeping track of the current node, as well as the previous node. If the current node is even, then the previous node’s next pointer is set to point to the current node’s next node and the current node is set to point to the next node’s next node. This effectively removes the current node from its current position and inserts it after the next node.

9. Is it possible to reverse only the first half of a linked list in C++? If yes, then how?

Yes, it is possible to reverse only the first half of a linked list in C++. This can be done by using a slow and fast pointer approach. The slow pointer will advance one node at a time while the fast pointer will advance two nodes at a time. When the fast pointer reaches the end of the list, the slow pointer will be at the middle of the list. At this point, the first half of the list can be reversed by changing the next pointers of the nodes.

10. In a circular linked list, is it possible to find out if the next element of a pointer points to itself or not? If yes, then how?

Yes, it is possible to find out if the next element of a pointer points to itself or not. To do this, you can simply check if the pointer’s next element is equal to the pointer itself. If it is, then the pointer is pointing to itself and the linked list is circular.

11. How can you check whether a given linked list contains a cycle in it or not?

There are a few ways to check for a cycle in a linked list. One way is to keep track of the nodes you visit as you iterate through the list. If you ever visit a node a second time, then you know there is a cycle. Another way is to keep track of the nodes in the list using a hash table. If you ever try to add a node to the hash table and it is already in the table, then you know there is a cycle.

12. What’s the best way to check for looping in a linked list using recursion?

The best way to check for looping in a linked list using recursion is to keep track of the nodes that have been visited. If a node is visited twice, then there is a loop.

13. How many number of operations are required to identify a loop in a linked list?

There are two main ways to identify a loop in a linked list. The first is to keep track of each node as you visit it, and see if any node is visited twice. If so, then you have a loop. The second way is to have two pointers, one that moves one node at a time, and another that moves two nodes at a time. If the two pointers ever meet, then you have a loop.

14. How does Floyd’s algorithm work?

Floyd’s algorithm is used to detect whether or not a linked list is circular. It does this by using two pointers, one slow and one fast. The slow pointer moves one node at a time, while the fast pointer moves two nodes at a time. If the linked list is circular, then at some point the two pointers will end up pointing to the same node.

15. What is the difference between a sorted and unsorted linked list? Which one would you recommend in certain situations?

A sorted linked list is a data structure where the nodes are arranged in order from smallest to largest (or vice versa). An unsorted linked list is a data structure where the nodes are not arranged in any particular order.

There are pros and cons to both types of linked lists. A sorted linked list is easier to search through because the nodes are already in order. However, an unsorted linked list is easier to insert new nodes into because you don’t have to worry about maintaining the sorted order.

In general, I would recommend using a sorted linked list if you need to frequently search through the list. I would recommend using an unsorted linked list if you need to frequently insert new nodes into the list.

16. How do you sort a linked list in ascending order?

To sort a linked list in ascending order, you will need to traverse the list and compare each node’s value to the values of the nodes that come before it. If the current node’s value is less than the value of the node before it, you will need to swap the two nodes’ positions in the list. Once you have compared all of the nodes and swapped them as necessary, the linked list will be sorted in ascending order.

17. What are some common use cases for circular linked lists?

Circular linked lists are often used in situations where data needs to be accessed in a sequential manner, but there is no defined beginning or end to the data. For example, a circular linked list could be used to implement a queue, where new data is added to the end of the list and data is removed from the front of the list. Another common use case for circular linked lists is in computer networking, where they can be used to implement a ring topology.

18. How do you create a copy of a linked list?

To create a copy of a linked list, you need to create a new node for each element in the original list, and then link the new nodes together in the same order as the original list.

19. What’s the best way to search for specific data in a linked list?

The best way to search for specific data in a linked list is to use a linear search algorithm. This will involve traversing the entire list until the desired data is found.

20. What is the maximum size allowed for a linked list?

There is no maximum size for a linked list.