2.1 Algorithms

2.1 Algorithms

1. computational thinking

   • the thought process involved in formulating a problem and its solution(s), so that a computer human or machine can effectively carry out
   • to effectively solve problems you need to...
     • decompose
     • abstract
     • algorithmic thinking
     • create algorithms
   • flowcharts
     • display an algorithm in diagram form using symbols and arrows to show to flow of information
   • pseudocode
     • a structured use of English used to define the steps needed to solve a problem
   • KEY TERMS
     • algorithm
       • steps to provide a solution to a problem, usually represented in flowcharts or pseudocode
     • decompose
       • breaking down a large problem into smaller sub-problems
     • abstraction
       • representing 'real world' problems in a computer using variables and symbols and removing unnecessary elements from the problem
     • algorithmic thinking
       • identifying the steps involved in solving a problem
     • sequence
       • completing steps in the order which they must happen
     • selection
       • where a choice is made in a program on a condition or outcome
     • iteration
       • act of repeating or looping specific sections of code

2. flowcharts

   • flow diagrams visually represent the steps that make an algorithm
   • a standard set of shapes are used to represent different types of step, such as running a sub-process or taking one path or another depending on a condition being met.
   • the arrows in a flow diagram represent the flow of control through the algorithm.
   • representing if/else if/else in flowcharts
     • a selection structure is used when multiple conditions are to be tested resulting in a different thing happening each time
     • these structures can be represented in flow diagrams using multiple decision diamonds flowing into each other from their ''no'' branches.
   • representing switch-case structure can be used to check whether a single variable has been assigned one of any possible values
     • switch case structures are neater than using if/if else when testing for a particular value of a single variable but they cannot test multiple conditions that involve different variables.

3. Pseudocode

   • pseudocode uses English. It mimics how your code may look in the programming language BUT IT DOESN'T HAVE TO BE EXACT
   • useful terms to use
     • START
     • IF
     • ELIF
     • ELSE
     • FOR
     • WHILE TRUE
     • ENDIF
     • END
   • COMPARISON OPERATORS
     • = EQUAL TO
     • != not equal to
     • < less than
     • <= less than or equal to
     • > greater than
     • >= greater than or equal to

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