1 - Fundamentals of Algorithms

Question 1

What is an algorithm?

e.g. directions

Answer 1

An algorithm is a sequence of steps that can be followed to complete a task. A computer program is an implementation of an algorithm and an algorithm is not a computer program

Question 2

What is decomposition?

e.g. recipe

Answer 2

Decomposition is breaking a problem into a number of sub-problems, so that each sub-problem achieves an identifiable task, which might itself be further subdivided

Question 3

What is abstraction?

e.g. London tube map

Answer 3

Abstraction is the process of removing unnecessary detail from a problem

Question 4

What is a model for how a computer operates?

Answer 4

The input-process-output model helps to show how a computer operates.

Question 5

What is the input stage in a computer, and where does it take place in the algorithm?

Answer 5

The input stage is the flow of data into the process from outside the system. It takes place at the start of the algorithm

Question 6

What is the process stage in a computer, and where does it take place in the algorithm?

Answer 6

The process stage includes all the tasks required to affect a transformation of the inputs. It takes place in-between the input and output stage

Question 7

What is the output stage in a computer, and where does it take place in the algorithm?

Answer 7

The output stage is where the data and information flow out of the transformation process, and it takes place at the end of the algorithm

Question 8

What are flowcharts?

Answer 8

Flowcharts are diagrams that represent an algorithm

Question 9

What does the flow line mean?

Answer 9

The flow line shows the sequence of operations. These must go in through one box and out of the other.

Question 10

What does a terminal symbol mean?

Answer 10

The terminal symbol denotes the start or end of the algorithm

Question 11

What does the processing symbol mean?

Answer 11

The processing symbol denotes a process to be carried out

Question 12

What does a decision symbol mean?

Answer 12

A decision symbol is used to represent the operation in which there are 2 alternatives

Question 13

What structures can be used for flowcharts?

Answer 13

Sequence, Selection and Iteration structures

Question 14

What is pseudocode?

Answer 14

Pseudocode is a way of developing an algorithm, which consists of natural language-like statements that precisely describe the steps required

Question 15

What are assignment operators?

Answer 15

Operators that set the value of the variable in pseudocode

Question 16

How do you input something in pseudocode?

Answer 16

VAR

Question 17

How do you output something in pseudocode?

Answer 17

OUTPUT (or PRINT, DISPLAY, SHOW, RETURN) ‘information’

Question 18

How do you process or compute something in pseudocode?

Answer 18

COMPUTE, CALCULATE, DETERMINE

Question 19

How do you comment on your pseudocode?

Answer 19

By using # key

Question 20

How do you add selection in pseudocode?

Answer 20

By using IF, THEN, ELSE, ENDIF statements

Question 21

How do you represent pseudocode as a flowchart (and vice versa)?

Answer 21

By matching each statement with whether it is an input, output, process, terminal or decision statement

Question 22

How do we use a trace table to identify how simple algorithms work?

Answer 22

A trace table is a technique used to see if any logic errors are occurring whilst the algorithm is being processed

Question 23

How can visual inspection be used to see how a simple algorithm works?

Answer 23

By looking at it to see if any logic errors occur based on the expected outcome and the actual outcome of the algorithm

Question 24

What types of loops can be used in pseudocode?

Answer 24

FOR loop, WHILE loop, REPEAT … UNTIL loop

Question 25

When will you use a FOR loop and how should you use it?

Answer 25

You use a FOR loop when you know how many times you want a loop to repeat:
E.g.
FOR I

Question 26

When will you use a WHILE loop and how should you use it?

Answer 26

You use a WHILE loop when you loop a code based on a certain condition, which is checked at the start:
e.g.
WHILE a < 5
OUTPUT a
ENDWHILE

Question 27

When will you use a REPEAT … UNTIL loop and how should you use it?

Answer 27

You use a REPEAT UNTIL loop when you loop a code based on a certain condition, which is checked at the end:
e.g.
REPEAT
OUTPUT a
UNTIL a < 5