Topic 4: Computational thinking

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4.1.1:Procedural Thinking

An algorithms is a set of instructions to be followed in a clear manner.

Procedural thinking

Eg. A procedural algorithm for making a cup of tea:

1. Put water in kettle

2. Turn on kettle

3. Get a cup

4. Place tea bag in cup

5. Pour water in cup

6. Wait

7. Remove tea bag

8. Stir

Each step could be broken down further for a computer as opposed to a human because computer's cannot make assumptions.

Eg. For step 1:

1. find the kettle

2. take the kettle to the tap

3. turn on tap

4. wait until kettle is full

5. Turn off tap

6. Take kettle to base

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4.1.2:

Algorithms require an order and number based system to it.

Each step is a sub-procedures the break down our problem.

Top down programming: Looking at the big problem, breaking it down into little problems and then solves them one at a time. This is the way that we should work in our algorithms unit. There is also Bottom up programming: Solving little problems without looking at the bigger picture.

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4.2.6: Two ways of representing algorithms

1. Pseudocode (4.2.5-6)

Uses conventional construction of computer code with less emphasis on syntax

Describes logical flow of a program

A program flow might "branch" (If statement in Java) or a "loop" (for or while loop in Java) or "Jump to" ("go back to step 4) 2. Flow Diagrams (4.2.4)

Decision tree that shows logical flow of a program using standardized diagram notation.

The notation for flow diagrams is pictured below:

While loop- runs until a condition tests true of false

for loop- runs a set number of times

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PSEUDOCODE

Keywords:

input

output

if then else

loop

mod

div

AND

OR NOT

Variables: In uppercase

NAME

Comment: //

Methods: Mix case names (getRecord)

dot notation to invoke