Interpreting, Correcting & Completing Algorithm

Test yourself

Interpreting Algorithms

Reading other peoples' code is sometimes the most difficult part of writing software, so it needs some practice.

Interpreting algorithms

Given an algorithm you should be able to read it and explain what it does.
This needs some practice, but there are some things you can look out for.

Look out for identifiers

Identifiers are the names of variables, constants, and subroutines.
These often give strong clues about the purpose of an algorithm.

Identify inputs and outputs

Check what is being input and output in the algorithm for clues about its purpose.

Examine output messages

Output messages often format the result of an algorithm in a human readable way.

Look for comments

Comments are descriptions of the code.
Comments will often state the purpose of a given algorithm.
Comments are often the clearest way to identify an algorithm.

Correcting Algorithms

As well as knowing what an algorithm does, it's important to be able to fix it if it all goes wrong.

Incorrect identifiers

A common mistake in programs is incorrect identifiers.
Be very careful with uppercase and lowercase letters.
Be careful with similar looking characters:
- 0 and O.
- 1 and l (lower case L).

Incorrect operators

Look out for the difference between similar operators such as testing if a number is less than another, rather than less than or equal to the other.

Missing processes

Sometimes a line of code has been forgotten, which can lead to issues such as infinite loops, where the code will never end.

Completing Algorithms

Some exam questions will ask you to state the output of an algorithm.

Interpreting the algorithm

The first step for this type of question is to try to identify what the algorithm does.
If you can interpret the algorithm, then it will be much easier to follow it.

Trace tables

You can draw a table with a column for each variable in the algorithm.
Use this table to keep track of the value of each variable, and carefully follow through the code until the end.
Finally, the trace table should include your answer.

1Components of a Computer

1.1Structure & Function of the Processor

1.1.1Structure of the CPU

1.1.2Fetch, Decode, Execute Cycle

1.1.3Factors Affecting CPU Performance

1.1.4CPU Architecture

1.2Types of Processors

1.2.1CISC & RISC

1.2.2Multicore & Parallel Cores

1.3Input, Output & Storage

1.3.1Computer Systems

1.3.2Magnetic Storage

1.3.3Optical Storage

1.3.4Types of Optical Storage

1.3.5Types of Memory

1.3.6Flash Memory

1.3.7Virtual Memory

2Software & Software Development

3Exchanging Data

4Data Types, Data Structures & Algorithms

4.1Data Types

4.1.1Data Types

4.1.2Arrays & Strings

4.1.3Representing Numbers

4.1.4Binary Arithmetic

4.1.5Hexadecimal

4.1.6Converting Binary Numbers

4.1.7Floating Points in Binary

4.1.8Floating Point Arithmetic

4.1.9Bitwise Manipulation

4.1.10Character Sets

4.2Data Structures

4.2.1Arrays, Linked Lists & Queues

4.2.2Graphs, Hash Tables & Stacks

4.2.3Trees

4.3Boolean Algebra

4.3.1Computational Logic

4.3.2Boolean Logic

4.3.3Karnaugh Maps

4.3.4Boolean Identities

4.3.5Flip Flops & Adder Circuits

5Legal, Moral, Cultural & Ethical Issues

5.1Computing Related Legislation

5.1.1Data Protection Act (1998)

5.1.2Computer Misuse Act (1990)

5.1.3Copyright Designs and Patents Act (1988)

5.1.4Regulation of Investigatory Powers Act (2000)

5.2Moral & Ethical Issues

5.2.1Online Activity Tracking

5.2.2Censorship

5.2.3Cultural Issues

5.2.4Environmental Issues

5.2.5Layout, Colour Paradigms & Character Sets

6Elements of Computational Thinking

6.1Thinking Abstractly

6.1.1Abstraction

6.2Thinking Procedurally

6.2.1Decomposition

6.3Thinking Logically

6.3.1Pseudocode & Flow Diagrams

7Problem Solving & Programming

7.1Programming Techniques

7.1.1Programming Fundamentals

7.1.2Modularity

7.2Programming Construction

7.2.1Integrated Development Environments

7.2.2Testing

8Algorithms

8.1Algorithms

8.1.1Interpreting, Correcting & Completing Algorithm

8.1.2Sort Algorithms

8.1.3Insertion & Merge Sort

8.1.4Search Algorithms

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