Chapter 9 - Algorithm Design and Problem-solving

Algorithm

Solution to a problem expressed as a sequence of defined steps

Three basic programming constructs:

• Sequence: The steps are performed one after another
• Selection: Depending on conditions different steps are performed.
• Repetition/Iteration/Loops: A set of steps are performed one after another

Pseudocode

• Writing an algorithm using plain English and programming-like structures to outline the logic of the problem
• For syntax it is recommended to use the pseudocode guide given in the syllabus.

Flowchart

A diagram that uses symbols and arrows to show a visual representation of the algorithm

Action	Symbol	Description
Flowline		Represents control passing between the connected shapes.
Process		Represents something being performed or done
Subroutine		Represents a subroutine call that will relate to a separate, non-linked flowchart
Input Output		Represents the input or output of something into or out of the flowchart.
Decision		Represents a decision (Yes/No or True/False) that results in two lines representing the different possible outcomes.
Terminator		Represents the ‘Start’ and ‘Stop’ of the process.