Problem Decomposition (Cambridge International IGCSE Computer Science)

Spec point — "(b) Understand how a problem can be decomposed into its component parts"

Problem Decomposition

What is decomposition?

• Decomposition is the process of breaking down a large problem into a set of smaller problems

• Benefits of decomposition are:

  • Smaller problems are easier to solve
  • Each smaller problem can be solved independently of the others
  • Smaller problems can be tested independently
  • Smaller problems can be combined to produce a solution to the full problem

• Modern computer games are a good example of using decomposition to break down the complexity of the problem into more manageable'chunks'

• Creating an entire game at once would be challenging and inefficient, so it could be decomposed into:

  • Levels- Levels can be designed/created/tested/ independently of other levels
  • Characters- The mechanics of characters in the game can be designed and created by a separate team
  • Landscape- The art team can work on the visual aspects of the game without needing to understand how the game is programmed

• Once all of the smaller problems are completed, joined together a complex game has been created

Inputs, processes, outputs and storage

• Decomposing a problem requires developers to think about four component parts:

  • Inputs: data entered into the system
  • Processes: subroutines and algorithms that turn inputs and stored data into outputs
  • Outputs: data that is produced by the system, such as information on a screen or printed information
  • Storage: data that is stored on a physical device, such as on a hard drive or in memory whilst the program is running

Example - Area of a rectangle program