1. What is Computer Science?
What it is not
Game Play or Game Development
Animated Film Making
Web Site Development
Definition
Computer science is the study and application of ways to represent problems in such a manner to make those problems amenable to being solved partially or completely with computer programs (i.e., software).
Algorithms + Data Structures = Computer Programming. Donald Knuth

2. What is Computer Science?
What do computer scientists do?
Development
Programming or web development in a multitude of industries: business, retail, communications, entertainment, government, or defense.
Operations and Maintenance
Installing, configuring, monitoring or repairing computer equipment
Customer service
Networks and Security
Installing, configuring, monitoring or repairing computer networks
Network security: network protection, intrusion detection.
Management
Supervision of developers, operations, or networks
Teaching and/or Research

3. CS Fundamentals
Computer science is the study and application of ways to represent problems in such a manner to make those problems amenable to being solved partially or completely with computer programs (i.e., software).
“Represent Problems”: The “stuff” on which you make decisions needs to be encoded in a manner which the computer can understand.
Information Representation
Data Structures
Data Design
“Computer Programs”: The instructions which the computer follows to accomplish the task at hand.
Software
Programs
Algorithms
So then, fundamentally, we need to know how to encode data (information representation) and write instructions (algorithms).

4. CS Fundamentals Information Representation
What basic kinds of information does the world contain?
Numbers
Characters (i.e. Letters or Symbols)
Logicals
Instructions or Commands
Colors or Sounds
References (think house address or citation)
How can we organize it?
Arrays: a collection of the same thing
Records (or Structures): a collection of different things
How does the computer store the data?
All information on the computer is stored as a number
So a number is a number, but characters, instructions, etc. are also numbers – so how does the computer tell the different kinds of info apart?

5. CS Fundamentals Information Representation
Data Typing: The kind (or type) of information is determined by the programmer telling the computer (via the program) what kind of information the number represents. (data typing example)
Encoding 101
Logical: ‘1’ means yes and ‘0’ means no
Instruction or Command
Color or Sound (paint, paint-by-number example, digital sound)
Character or Symbol (ASCII Table)
Number (intro to binary, programming example)
Reference (think house address or citation)
Information Representation Challenges
Fundamental types above tend to be too simple and static
So we need flexibility in specifying types
Modern languages permit new type definitions for various problems

6. CS Fundamentals Algorithms
Algorithm Definition: A specific, well defined procedure which has an end for accomplishing some task
Three Algorithmic Constructs
Sequence
Decision (or Selection)
Looping
Examples
Rock, paper, scissors
Exercises
Pass the Potatoes, Please
Computation Exercise
Algorithmic Challenges
Fundamental programming operations tend to be “mathy”
Need flexibility for specifying new non-mathy operations
Programming languages commonly provide capabilities for new operations

7. An Example of Data Typing
In the example below which computes the average of a set of test scores we have four pieces of information:
The number of test scores
The actual test scores
The sum (or total) of all the scores
The average of the scores (i.e., the total divided by the number of scores
The word “int” or “double” (in bold) in front of the variable name indicates how the number is to be interpreted when the program executes.
int num = 3;
double scores[num] = {94, 96, 99};
double total = 0.0;
double average = 0.0;
total = scores[0] + scores[1] + scores[2];
average = total / num;
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8. Algorithm Example Rock, Paper, Scissors
Each player thinks of either a rock, paper or scissors
One player says, “Rock, paper, scissors, shoot!!”
Each player shows object he/she was thinking of (an R, P, or S)
If P1 is R & P2 is S OR P1 is P & P2 is R OR P1 is S & P2 is P
Player 1 wins and gloats
Otherwise
Player 2 wins and gloats
P1 Wins? N
Think
Speak
Show Choice
P2 Gloats
P1 Gloats
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9. Algorithm Example (cont.) Rock, Paper, Scissors
Each player thinks of either a rock, paper or scissors
One player says, “Rock, paper, scissors, shoot!!”
Each player shows the object he/she was thinking of (i.e., R, P, or S)
If (P1 is R & P2 is S) OR (P1 is P & P2 is R) OR (P1 is S & P2 is P)
Player 1 wins and gloats
If (P2 is R & P1 is S) OR (P2 is P & P1 is R) OR (P2 is S & P1 is P)
Player 2 wins and gloats
Otherwise
Play game again
P1 Wins? N
P2 Wins? Y
Think
Speak
Show Choice
P2 Gloats
P1 Gloats Y
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10. Algorithm Exercise Pass the Potato
Develop an algorithm to solve the objective below, given certain restrictions:
Objective: Be the first team to move the potato from the first person in your row to the last.
Restrictions:
All team players must remain in their seats, and the seats in their area, at all times.
If you are handling the potato for the first time, then you may
Hand the potato to the person on your left or right
Toss the potato to a person in your row to the left, but not past more than one person
If you are handling the potato the 2nd, 3rd, 4th, .... time, then you may
Toss the potato to any person in your row
GO!!
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11. Algorithm Exercise Computation
Exercise the following algorithm:
Get numbers A and B from the instructor
If B equals 0, then go to step 7
Set C equal to the remainder of A / B
Set A equal to B
Set B equal to C
Repeat at step 2
Stand up and, when asked, announce the final value of A
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