Data Structures A Level Computer Science AQA Revision Questions and Answers

What is a queue? A First In First Out Data Structure. What is a stack? A LIFO, last-in first-out data structure. Define Abstract data type An abstract data type is a logical description of how the data is viewed and the operations that can be performed on it, but this is not necessarily known to the user. What are queue's used in? Characters typed in a keyboard are held in a queue in a keyboard buffer. Queues are useful in simulation programs simulates customers. Output waiting to be printed. What is abstraction? The removal of unnecessary details from a program making it easier to solve. What are the following operations needed for a queue? Enqueue(item): Adds a new item to the rear of the queue. deQueue(): Removes the front item from the queue and returns it. IsEmpty(): Test to see whether the queue is empty. IsFull(): Test to see whether the queue is full. What is dynamic data structure? A dynamic data structure refers to the collection of data in memory that has the ability to grow or shrink in size, it does this with the aid of the heap which is a portion of memory from which space is automatically allocated or de-allocated as required. Very useful for implementing data structures like queues. Example is a lists. What is static data structure A static data structure such as static array is fixed in size, and cannot increase in size or free up memory whilst the program is running.