Algorithms

• An algorithm is a precise set of instructions for solving a specific problem or task — precise means unambiguous, every step has exactly one meaning.
• There are three ways examiners expect you to design/represent an algorithm: structure diagrams (top-down hierarchy), flowcharts (visual shapes + arrows), and pseudocode (structured English-like text).
• Structure diagrams break a big system down into smaller and smaller sub-problems — like a family tree of tasks.
• Flowcharts use specific shapes: ovals for start/stop, parallelograms for input/output, rectangles for processes, and diamonds for decisions — connected by arrows showing the flow of control.
• Pseudocode is more structured than plain English but must never use real programming syntax like print() or semicolons — that loses marks in the exam.
• To explain an existing algorithm, you look at its inputs, its processing steps, its outputs, and (for complex ones) any comments, its context, or you test it with sample data.
• If a question just says "write an algorithm" with no format specified, default to pseudocode — it's faster and it's what examiners expect unless told otherwise.

Think about a recipe for making toast: put bread in toaster → wait 2 minutes → take bread out → spread butter. That's an algorithm — it's a sequence of exact, unambiguous steps that, if followed correctly by anyone (or any computer), always solves the same problem the same way.

The exam definition is short but every word matters: an algorithm is a precise set of rules or instructions to solve a specific problem or task. "Precise" is the key word — vague instructions like "cook it until it's done" aren't an algorithm, because different people would interpret "done" differently. A real algorithm might say "heat for exactly 4 minutes at 200°C."

Algorithms don't have to be written as computer code. Before a programmer ever writes a line of Python or Java, they usually design the algorithm first using one of three tools, because it's much easier to spot logic mistakes in a diagram or in plain-ish English than buried inside code syntax:

Structure diagrams top-down design decomposition

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flowchart flow of control what how

Pseudocode logic