1. Algorithms & Pseudocode

2. Algorithms An algorithm is a detailed set of steps to solve a problem
It states the actions to be executed and the order in which they are to be completed
Algorithms can be described using pseudocode or a flowchart
Algorithms are fundamental to computer programming

3. Developing an algorithm
High Level Algorithm
Written in pseudocode or drawn as a flowchart, it describes how the problem will be solved without the fine detail
Detailed Pseudocode
Expands the logic of the high level algorithm to closely match a real program
Real Code
Line by line conversion of the pseudocode to real code.

4. Important Constructs
There are 3 important constructs used in algorithms and coding that you need to be familiar with:
Sequence
The order that instructions are executed. Order is important eg:
Clean teeth
Get out of bed
Selection
Making a decision based on certain conditions eg:
If its raining then I’ll stay indoors
Else I’ll go to the park
Iteration
Another name for repeating a set of actions
While I feel hungry
Eat more food

5. Pseudocode
Pseudocode is an artificial language that helps programmers develop algorithms.
It is intended to be easy to read and free from the strict formal syntax of a programming language
The rules of pseudocode are reasonably straightforward – there should be a line of pseudocode for every line of real code in your program

6. Example 1 - Student grades
Task: A program is required to output ”passed” if a student achieves 60 or more marks otherwise failed
High Level Algorithm
Pseudocode
If student's mark is greater than or equal to 60
Display"passed"
else
Display "failed"
If mark >= 60
Print "passed"
else
Print "failed"
In this example the problem to be solved, high level algorithm and pseudocode are similar because of the very fact that it is a simple program.
However, that should not prevent you from completing the process!

7. Example 2 – Class Average
Task: A program is required to input the individual marks and calculate the average score for a class of 10 students
High Level Algorithm
Pseudocode
Initialise variables
Loop
add 1 to count
input mark
calculate average
Until count > 10
Display average
average  0, class-total  0, mark  “”
For count  1 to 10
mark  userinput (”enter student’s marks”)
class-total  class-total + mark
average  class-total/count
Next count
Useroutput (“class average is “, average)
Now the value of the high level algorithm becomes clearer.
It shows the “big picture” of how the problem is to be solved
Finer detail is added in the pseudocode ie:
Variables to be used
type of loop (for or while)
Calculation of average