Algorithms and Flowcharts

An algorithm is a finite, unambiguous sequence of steps; a flowchart draws those steps as shapes and arrows.

Beginner

An algorithm must be finite (it ends), definite (each step is clear) and effective (each step can actually be done), with defined inputs and outputs.

A flowchart visualises an algorithm:

Shape	Meaning
Oval	Start / end
Parallelogram	Input / output
Rectangle	Process (a calculation)
Diamond	Decision (yes / no)

Example — find the larger of two numbers:

START → read a, b → is a > b ? → yes: print a
                               → no:  print b → END

Writing the algorithm first saves a lot of debugging later.

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