Circular Queue
Explore the concept of circular queues in this lesson, where you learn to implement a fixed-size queue with pointers that wrap around using the modulo operator. Understand how circular queues solve wasted space issues in array-based queues and maintain O(1) time complexity for enqueue and dequeue operations. This lesson helps you grasp why circular queues are essential in systems with fixed memory, such as OS buffers and streaming pipelines, and prepares you for related coding interview problems.
Before introducing circular queues, it is important to understand the problem they address.
In a simple array-based queue, elements are added at the rear and removed from the front. As dequeue operations occur, the front index advances. Over time, the positions at the beginning of the array become empty and are never used again. Eventually, the rear reaches the end of the array, and the queue appears full; even though much of the array is actually empty.
This is a serious waste of memory. Consider a queue of size 5 that has had two dequeue operations:
The rear is at the last index. If we try to enqueue a new element, the queue reports overflow, even though positions 0 and 1 are free. A circular queue solves this directly.
What is a circular queue?
A circular queue is a queue in which the last position of the array is connected back to the first ...