CHAPTER 9: ALGORITHM DESIGN AND PROBLEM-SOLVING

9.1 COMPUTATIONAL THINKING SKILLS

9.1.1 Abstraction

Definition: The process of removing unnecessary details to focus on essential features.

Need:

Manage complexity
Create models of real-world systems

Benefits:

Focus on what matters
Reusable solutions

9.1.2 Decomposition

Definition: Breaking down complex problems into smaller, manageable sub-problems.

Benefits:

Easier to solve smaller problems
Can work on different parts independently
Leads to modular programming (procedures/functions)

9.2 ALGORITHMS

9.2.1 Algorithm Representation

Methods:

Structured English
Flowchart
Pseudocode

Components:

Input
Process
Output

Basic Constructs:

Sequence (order of execution)
Selection (IF, CASE)
Iteration (loops)

9.2.2 Pseudocode Guidelines

Input/Output:

<TEXT>

INPUT variable
OUTPUT variable/value

Assignment:

<TEXT>

variable ← value

Selection:

<TEXT>

IF condition THEN
 statements
ELSE
 statements
END IF

CASE OF variable
 value1 : statement
 value2 : statement
 OTHERWISE : statement
END CASE

Iteration:

<TEXT>

FOR counter ← start TO end
 statements
NEXT counter

WHILE condition
 statements
END WHILE

REPEAT
 statements
UNTIL condition

9.2.3 Stepwise Refinement

Process:

Start with general solution
Gradually add detail
Continue until can be programmed