Insert at End of Circular Linked List in DSA C - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a circular linked list?

A circular linked list is a linked list where the last node points back to the first node, forming a circle with no NULL end.

beginner

Why do we need a special method to insert at the end of a circular linked list?

Because the last node points to the first node, we must update the last node's next pointer to the new node and the new node's next pointer to the first node to keep the circle intact.

beginner

Inserting at the end of an empty circular linked list results in what?

The new node points to itself, making it both the first and last node in the list.

intermediate

What pointers are updated when inserting a new node at the end of a non-empty circular linked list?

The current last node's next pointer is updated to the new node, and the new node's next pointer is set to the head (first node).

intermediate

What is the time complexity of inserting at the end of a circular linked list if we do not maintain a tail pointer?

O(n), because we must traverse the list to find the last node before inserting.

What does the last node in a circular linked list point to?

A The previous node

B The first node

C Itself

D NULL

In a circular linked list, the last node points back to the first node to form a circle.

When inserting at the end of an empty circular linked list, what should the new node's next pointer be?

A Itself

B NULL

C The head node

D The previous node

The new node points to itself because it is the only node, forming a circle.

Which pointer must be updated to insert a new node at the end of a circular linked list?

A Both the last node's next pointer and the new node's next pointer

B The new node's next pointer only

C The last node's next pointer only

D The head pointer only

Both pointers must be updated to maintain the circular structure.

If you do not keep track of the last node, how do you find where to insert the new node at the end?

A Insert after the second node

B Insert at the head

C Traverse the list until the node whose next points to head

D Use a stack

You must traverse to find the last node whose next points to the head.

What is the time complexity of inserting at the end if a tail pointer is maintained?

A O(n^2)

B O(log n)

C O(n)

D O(1)

With a tail pointer, insertion at the end is done in constant time.

Explain step-by-step how to insert a new node at the end of a circular linked list.

Think about how the circle is maintained after insertion.

Describe the difference in insertion at the end of a circular linked list when a tail pointer is maintained versus when it is not.

Consider how knowing the last node helps.