GCSE Link: None

A circular queue is a static abstract data type which stores a sequence of items.

In a linear queue, space can be wasted when data is dequeued from the front and never re-used. Circular queues fix this problem by using wrappable pointers which go back to the start if they go past the end.

Diagram 1 shows some operations being carried out on a circular queue.

Diagram 1

---

What is the time complexity of the enqueue and dequeue operations for a queue?

They are both O(1) (constant time), because the items never need to be shifted.

---