1.2.1 + 1.2.4 What algorithms are and how they are expressed The purpose of a given algorithm and how it works

Question 1

Define:

Algorithm

Answer 1

A well-defined set of step-by-step instructions to solve a problem

Question 2

Fill The Blank:

An algorithm is language ………………

Answer 2

Independent

Question 3

State:

Give 4 requirements of an algorithm

Answer 3

• Clear
• Clear defined outputs and inputs
• Simple
• Language independent

Question 4

State:

3 advantages of an algorithm

Answer 4

• Easy to understand by anyone
• Step by step representation of a solution to a given problem
• Initial problem is broken down into steps, which means it is easier to convert into code

Question 5

State:

2 disadvantages of algorithms

Answer 5

• Can be time consuming to create
• Some constructs can be difficult to represent

Question 6

State:

The 4 ways an algorithm can be represented

Answer 6

• Flowchart
• Written Description
• Pseudocode
• Program Code

Question 7

Define:

Flowchart

Answer 7

Graphical diagram that represents an algorithm which can be used to solve a problem

Question 8

State:

2 advantages of using a flowchart to represent an algorithm

Answer 8

• Flow of the algorithm can be seen clearly
• Flowcharts are created using a standardised set of symbols so can be interpreted and understood by many people

Question 9

State:

2 disadvantages of using a flowchart to represent an algorithm

Answer 9

• Can become large and difficult to follow when representing a large program
• Changes to design may result in the flowchart being amended or redrawn

Question 10

Fill The Blank:

Written descriptions should be in …………… language or plain English. There is no set of …….. to follow when using written description but they should be …….., ……… and contain few/no specific ………

Answer 10

Natural, Rules, Clear, Simple, Details

Question 11

State:

2 advantages of using a written description to represent an algorithm

Answer 11

• No formal syntax, so many people can create a written description
• Automatic and natural to use ‘proper’ English

Question 12

State:

2 disadvantages of using a written description to represent an algorithm

Answer 12

• Temptation to create a complete description (complicating it)
• Failure to include every step required

Question 13

Define:

Pseudocode

Answer 13

An informal description that shows the flow of an algorithm and follows a similar structure to high level languages

Question 14

State:

3 advantages of using pseudocode to represent an algorithm

Answer 14

3 of:
* Can be converted into programming code with only minor changes to obey syntax of the language
* Can be easy to follow and understand even if errors are present in the pseudocode
* Changes can be added in quickly
* Can act as a link between the algorithm and the final program
* Explains the purpose of each line of code

Question 15

State:

2 disadvantages of using pseudocode to represent an algorithm

Answer 15

• Can be time consuming to write clear and well structured pseudocode to write the final program code
• Can be difficult to see the logical flow of the program

Question 16

Define:

Program Code

Answer 16

Code written to solve the problem which follows the rules of a selected programming language

Question 17

State:

3 advantages of using (draft) program code to represent an algorithm

Answer 17

• Very probable the person creating the algorithm will have programming knowledge
• Not necessary to use the correct syntax
• All the required constructs will be available to be included in draft code

Question 18

State:

2 disadvantages of using program code to represent an algorithm

Answer 18

• Easy to begin creating draft code but end up creating the final program code
• Full decomposition may not be completed

Question 19

Define:

Dry Run

Answer 19

Manually working through the code to trace the value of variables

Question 20

Define:

Trace Table

Answer 20

Tool used to test or dry run algorithms to make sure no logical errors occur while calculations are being processed

Question 21

State:

2 ways to test/check an algorithm works

Answer 21

• Visual Check
• Trace Table

Question 22

State:

2 advantages of using pre-written/library code

Answer 22

2 of:
* Save development time
* Save testing time
* Will be optimised (more efficient and error free)

Question 23

State:

1 disadvantage of using pre-written/library code

Answer 23

It may not be exactly what is required and may require editing to work for an unique problem

Question 24

Fill The Blank:

A ……….. check can be used to determine the purpose of the algorithm using pseudocode

Answer 24

Visual