Essential algorithms for GCSE and A Level Computer Science

Fundamental data structures

A feature of imperative programming languages, these abstractions of memory allow for the creation of higher order data structures.

What is a list?

A list is a collection of elements of different data types.  In practice, a list is either an array in disguise or an implementation of a linked list (see higher order data structures).  An array is typically used if the limits of the structure are known when the program is written — for example, we know chess is played on an 8x8 board.  Conversely, a list is used when the number of items is more variable such as a player’s inventory in an RPG game.  In reality, either an array or a list can usually

be used for the same purpose. 

Some programming languages support both arrays and lists while some only support one or the other.

List videos

What extra is in the book?

This algorithm / data structure has its own dedicated chapter in the book, which includes:

  1. Overview
  2. Typical applications / uses
  3. Typical operations
  4. The algorithm written out in simple-structured English
  5. The algorithm written out in pseudocode
  6. Full code listing Python
  7. Full code listing in Visual Basic
  8. Diagrammatic walk-through
  9. Efficiency discussion with reference to Big-O notation

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