Essential algorithms for GCSE and A Level Computer Science

Sorting algorithms

Routines that organise data in fundamental data structures in order.

What is a Merge sort?

A merge sort can sort a data set extremely quickly using divide and conquer. The principle of divide and conquer is to create two or more identical sub-problems from the larger problem, solving them individually and combining their solutions to solve the bigger problem. 

With the merge sort, the data set is repeatedly split in half until each item is in its own list.  Adjacent lists are then merged back together, with each item in the sub-list being entered into the correct place in the new, combined list.

Merge sort 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

A hard copy of the book is available on our shop and a free PDF copy is included for all premium subscribers.