Algorithms Notes

Question 1

Computer programs:

To communicate with a computer program, we have to tell it what to do, step by step. This is done using…?

Answer 1

a computer program. In order to write a computer program, we must first analyse the task and there are a number of techniques to help with this.

Question 2

Algorithm…?

Answer 2

A set of step by step instructions for solving a problem. It is written using ordinary English.

Question 3

Structure diagram…?

Answer 3

Are a pictorial way of representing the logic of an algorithm.

Question 4

Pseudocode…..?

Answer 4

A method of expressing the logic of an algorithm using statements.

Question 5

Algorithms normally start with an _____ and end with an _____.

Answer 5

Input, output.

Question 6

Algorithms can be thought of as…?

Answer 6

• A series of mechanical, repetitive, routine processes.
• A complete set of unambiguous instructions needed to perform a task or solve a problem.
• A clear description of how a computer is to proceed in an organised way through a sequence of elementary steps (a computer program).

Question 7

Characteristics of an Algorithm…?

Answer 7

• unambiguous
• precise
• finite
• effective

Question 8

What Algorithms are used in computer systems…?

Answer 8

In any computer system, many algorithms are used. For example, some of the algorithms used by an ATM (Automatic Teller Machine) are:

• Checking that the correct pin number has been entered.
• Performing a withdrawal of cash
• Performing an account balance inquiry.

Question 9

Structure diagrams are used to…?

Answer 9

represent the logic of an algorithm. The first step is to break the algorithm into a beginning, a middle and an end.

Question 10

A structure diagram must be read in the correct order…?

Answer 10

first the name of the algorithm at the top and then the beginning, middle and end are read across from left to right.

Question 11

Structure diagram symbols:

A rectangle represents…?

Answer 11

Process, summary or name.

Question 12

Structure diagram symbols:

A polygon represents….?

Answer 12

Input or output.

Question 13

Structure diagram symbols:

Loop or iteration…?

Answer 13

Rounded Rectangle.

Question 14

Structure diagram symbols:

If statement or condition…?

Answer 14

Hexagon.

Question 15

Algorithms have 3 parts
Beginning…?
Middle …?
End…?

Answer 15

• initialize variables and totals, get inputs.
• main part, usually has loops and/or conditions (IF), processes, outputs.
• may have outputs, summary statements.