A queue is an abstract data type defining a list under a FIFO constraint: insertion (enqueue) occurs only at the rear and removal (dequeue) only at the front, with enqueue, dequeue, front, and isEmpty all required to run in O(1). Implementing this over a fixed array by keeping two indices, front and rear, is correct but leaks capacity — cells left behind the advancing front can never be reused — and the remedy is the circular-array interpretation, in which index advancement is defined modulo the array size so the storage wraps around and every cell stays reusable. The topic sits in the data structures branch of computer science and illustrates the general separation between an ADT (the contract of operations and their complexity) and a concrete implementation (the representation chosen to satisfy that contract).
A queue is an abstract data type defining a list under a FIFO constraint: insertion (enqueue) occurs only at the rear and removal (dequeue) only at the front, with enqueue, dequeue, front, and isEmpt…