1. CMPT 120
Lecture 2 - Introduction to Computing Science – Problem Solving, Algorithm and Programming

2. Last Lecture Introducing the course Little activity -> Thank you!
What is this course all about?
All we need is …
How is this course going to work?
Little activity -> Thank you!
Our first program!
Q&A
Summary

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

4. Reading Review
What is the single most important skill for a computer scientist?
Comments and ________ ________ can make your programs much easier for humans to parse. Use them liberally!
What is the difference between a natural language and a formal language?

5. Unit 0 What is Computing Science?
In the first week, we'll talk about what computing science is, where it comes from, why it's awesome, and start to learn about how it works.
You'll get set up with the tools that we'll be using in this class to help you become proficient computer scientists by the end of this course.
By the way, in computing, we count from 0 :)

6. 1st part of the course’s title: What is Computing Science?
Study of computation -> all aspects of problem solving
a.k.a. computational thinking
Source:

7. BTW: Computing or Computer Science?
“Computing science is as much about computers as astronomy is about telescopes."
From wiki: “Despite its name, a significant amount of computer science does not involve the study of computers themselves.”
Computer: a tool
Computing: field of study

8. Activity – Solving a Problem
What are the steps we go through when we solve a problem?
Take 5 minutes to …
Pair up
Pick a problem you both have experienced
Identify the steps you go through when you solved your problem

9. Steps of Problem Solving

10. What is an algorithm?
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 data it needs in order to work -> input
The result it produces -> output

11. More about algorithm
Video Algorithms from Khan Academy

12. Activity - Human meets alien!

13. How do we express an algorithm?
1. Use a natural language like English
Example – problem: compute final course grade
2. Use a mix of natural language and computer language -> pseudocode
3. Use a flowchart
4. In a diagram
Example – problem: build a shelving unit
5. In a video (verbal instructions and pictures)
Example – problem: make tea

14. Let’s give it a go! – Take 1 Problem: Solution:
Display a greeting on the screen
Solution:
Algorithm in English Comments
Write your 1) header block with a title, a general description of what you’re trying to do, author and date 2) algorithm steps
All lines should be preceded by a ________
Code
Translate your algorithm into Python using a new addition to our vocabulary: print. Note the parentheses and quotation marks. These are necessary.

15. Let’s give it a go! – Take 2
Problem:

16. Why do we need algorithms?

17. Today’s Review How can I express an algorithm?
How would I display = 12 on the screen?
What are the steps we performed when we solve a problem?
What do we put in a header?
What would print("Above\nBelow") produce on the screen?
Give an example of an algorithm?

18. Next Lecture Introduce Unit 1 – Automation – Chatbots
Can we build chatbots using what we know of Python so far, i.e., print, variables, strings input, lists, modules, etc…?
We shall see 