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An algorithm is a logical, step-by-step process for solving a problem. Algorithms are normally written using one of the following conventions:

• pseudo-code
• flowcharts
• written descriptions
• program code

An algorithm should be seen as a starting point before writing a program. It should include the required programming constructs to solve the problem, ie sequence, selection and iteration. The finished program should follow the steps the algorithm describes.

Before an algorithm can be designed, it is important to check that the problem is completely decomposed. You can find out more about decomposition on page 2 of this study guide. The decomposed problem should consider the following questions:

• What are the inputs into the problem?
• What will be the outputs of the problem?
• In what order do instructions need to be carried out?
• What decisions need to be made to solve the problem?
• Are any areas of the problem repeated?

Only when a problem is properly decomposed and understood can an algorithm design begin.