How do you implement a circular queue using a linked list?

To implement a circular queue using a linked list, you create a linked list with a fixed size and two pointers, front and rear.

A circular queue, also known as a ring buffer, is a linear data structure that follows the First-In-First-Out (FIFO) principle. It is called a circular queue because the last element points to the first element making a circular link. To implement this using a linked list, you need to create a linked list with a fixed size and two pointers, front and rear. The front pointer points to the first element in the queue and the rear pointer points to the last element.

To start, initialise the front and rear pointers to null. When you add an element to the queue (enqueue operation), check if the queue is full. If it's not, create a new node with the data and add it to the rear of the queue. Update the rear pointer to point to this new node. If the queue was empty, also update the front pointer to point to this new node. If the queue is full, you need to either throw an overflow error or overwrite the oldest data.

When you remove an element from the queue (dequeue operation), check if the queue is empty. If it's not, remove the node that the front pointer is pointing to and update the front pointer to point to the next node. If this was the last element in the queue, also update the rear pointer to null. If the queue is empty, you need to throw an underflow error.

To check if the queue is full or empty, you can either keep track of the number of elements in the queue or you can use the front and rear pointers. If the front pointer is null, the queue is empty. If the rear pointer's next element is the front pointer, the queue is full.

Remember, the key to implementing a circular queue using a linked list is managing the front and rear pointers correctly. If you do this, you can efficiently add and remove elements from the queue.