Writing & Amending Algorithms (Cambridge (CIE) IGCSE Computer Science)
Revision Note
Written by: Robert Hampton
Reviewed by: James Woodhouse
Algorithmic Thinking
What is algorithmic thinking?
Algorithmic thinking is the process of creating step-by-step instructions in order to produce a solution to a problem
Algorithmic thinking requires the use of abstraction and decomposition to identify each individual step
Once each step has been identified, a precise set of rules (algorithm) can be created and the problem will be solved
An example of algorithmic thinking is following a recipe, if the recipe is followed precisely it should lead to the desired outcome
A set of traffic lights is an example of how algorithmic thinking can lead to solutions being automated
Examiner Tips and Tricks
Writing algorithms in an exam can be challenging and time consuming. It's important to allocate your time carefully to not spend too little or too long writing an algorithm
You will likely make mistakes and rewrite your algorithm a few times. Use scrap paper or the back of your exam paper if possible to sketch out your ideas before committing to your answer. This will make your answer clearer, neater and easier to read, follow and understand
You may wish to chunk your algorithm into parts initially, for example, “This part will enter the grades”, “this part will calculate the total”, and “This part will allocate grades”. You can then put the whole algorithm together in order later
Make a plan before you start answering the question and writing your algorithm. A plan can be simple but allows you to order your thoughts, for example:
Part 1: Declare and initialise variables
Part 2: Allocate marks for each subject
Part 3: Allocate grades for each student's subject
Part 4: Include a loop
Part 5: Output all necessary data
Pseudocode does not have a syntax, therefore you can write an algorithm in any way which is easily understandable. Caution is advised to stick to IGCSE specification standards to ensure your answer is consistent and easy for examiners to follow
Be sure to use variable names and data provided in the question as given. Failure to do so will lose you marks
Remember to comment on your code. It helps both you and the examiner understand your answer and also awards marks in the mark scheme!
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