1. Topic: Introduction to Computing Science and Programming + Algorithm
CMPT 120
Topic: Introduction to Computing Science
and Programming + Algorithm

2. Last Lecture Introduced the course Little activity -> thank you!
What this course is about
Its resources
Little activity -> thank you!
Some questions
Our expectations
How to get ready for next lecture
How to participate during lecture
If we are on the waiting list …

3. Today’s Menu
Course Title: “Introduction to Computing Science and Programming 1”
This slide is from our Lecture 1.

4. Learning Outcomes
At the end of this course, a student will be able to:
Describe fundamental concepts pertaining to computing science
Computing science
Problem solving
Algorithm
Decomposition

5. i-clicker – Practice Session
About our 2 readings and more

6. What is Computing Science?
Study of computation -> all aspects of problem solving
-> a.k.a. computational thinking
Design and analysis
of algorithms
Formalization of
algorithms as programs
Development of computational devices (e.g.: computers) for executing those programs

7. We can hear what people have to say …
… about what Computer Science is!
-> Let’s follow some of the links listed under Resources on our course web site:
What is Computing Science? from Rochester Institute of Technology (video)
What is Computing Science? from code.org (video)

8. Computer versus Computing
Computer: a tool
“Despite its name, a significant amount of computer science does not involve the study of computers themselves.”
Computing: field of study
According to
Computing = Computation
Reference:

9. Subfields of Computing Science
Will come back to this topic at end of semester
Links listed under Resources on our course web site:
Description of Computing Science from Wiki
Areas of Research at SFU School of Computing Science

10. What is Programming?

11. Problem Solving Process
State the problem
a) Design solution(s) to problem -> solution is expressed as an algorithm
b) Identify data involved in problem
input
Structure and represent (abstract) data into algorithms/programs
output
Analyze the algorithm
Is it effective?
Is it efficient?
Implement algorithm into a computer program
Test program
Does it execute (run)?
Does it solve the problem?

12. Problem Solving Process – Example
There is no more milk.
Data: milk
Solution:
Buy more milk.
“Implement” the solution
Hum… can I???
Its describing a solution
to the problem without details.

13. Decomposition
What if the algorithm is not detailed enough to implement it and solve the problem?
Then we need to decompose it into “finer”, i.e., more detailed steps
Example:
Buy milk
Now, we can “implement” the solution since we have sufficient details.

14. Problem Solving Process - Activity
State the problem
Design solution(s) to problem -> algorithm
(input, internal data, output)
Analyzing the algorithm (effective?/efficient?)
Implement the algorithm
Have we solve the problem?
Problem:
Data:
Algorithm: 
Once we apply the algorithm, is the problem solved?

15. Algorithm - Definition
A finite sequenced set of unambiguous steps that, once executed, produces a result
Finite: This set of steps executes in a finite amount of time i.e. it should finish at some point
Sequenced: The steps must be executed in the order in which they are listed
Unambiguous: Each step is clear
Result: This result solves the initial problem
The algorithm also describes
The input (data) it is expecting
Internal data it is using
The output (result) it is producing

16. More about algorithm
Please, see the video “Algorithms from Khan Academy” listed under Resources on our home course web page

17. How do we express an algorithm?
Use a natural language like English
Example:
Problem: Let’s figure out our course final grade
Take all the grades we obtained in course activities (e.g., assignments, exams, etc…)
Compute each grade as a % of final grade

18. How do we express an algorithm?
Use a mix of natural language and computer language -> pseudocode
Example:
Problem: Let’s figure out our course final grade
Set final grade to 0
For each grade
Input the grade
Input the grade’s maximum (out of) (gradedOutOf)
Input the grade’s % of the final grade (percentOfFinalGrade)
Compute the new grade: (grade * percentOfFinalGrade ) / gradedOutOf
Keep a running total: final grade = final grade + new grade
Print the final grade

19. How do we express an algorithm?
Start
Set final
grade to 0
Use a flowchart
Legend:
Have
Yes
All grades
read yet? No
Input the grade
Start and end of algorithm
Input the grade’s
maximum
Processing
Input the grade’s
% of the final grade
Input or Output
Compute
the new grade e
Decision
Keep a running
Total for final grade
Flow of execution
Print final grade
End

20. How do we express an algorithm?
4. In a diagram
Please, see ”Here is an awesome way of expressing an algorithm (Way #4)“ listed under Resources on our home course web page
5. In a video (verbal instructions and pictures)

21. Why do we need algorithms?

22. Summary i-clicker Practice Session
Computing Science -> Problem solving
Programming
Problem Solving Process
Algorithm
Decomposition
How to express them -> 5 ways
Why do we need them

23. Next Lecture Demo: Illustrate the Problem Solving Process
Experience what it means to create a computer program
Implement algorithm
into computer
program
State problem
Design algorithm
+ Identify data
Test it