Algorithm Design and Problem-Solving

This section focuses on developing and representing solutions to problems using flowcharts, structure diagrams, and pseudocode. These tools help in planning and documenting algorithms before implementation.

1. Flowcharts

Flowcharts are visual representations of algorithms, using standard symbols to depict different steps and decisions.

1.1 Flowchart Symbols

Symbol	Name
	Start/End
	Process
	Decision
	Input/Output
	Arrow

1.2 Flowchart Construction

1. Identify the start and end points of the algorithm.
2. Represent each step of the algorithm with an appropriate symbol.
3. Use arrows to show the flow of control.
4. Clearly label all symbols and arrows.

Example: A simple flowchart for adding two numbers.

2. Structure Diagrams

Structure diagrams are a way of representing the structure of a program, particularly using control structures like sequence, selection (if/else), and iteration (loops).

2.1 Structure Diagram Types

Type	Description
Sequence	Steps are executed in order.
Selection (if/else)	Different blocks of code are executed based on a condition.
Iteration (Loops)	Blocks of code are repeated until a condition is met.

2.2 Structure Diagram Construction

1. Identify the control structures needed for the algorithm.
2. Use the appropriate symbols to represent each structure.
3. Clearly label all blocks of code and decision points.
4. Use arrows to show the flow of control.

Example: A structure diagram for checking if a number is positive.

3. Pseudocode

Pseudocode is a human-readable, informal description of an algorithm. It uses plain English and programming-like constructs to outline the steps of an algorithm.

3.1 Pseudocode Constructs

Construct	Description	Example
Assign	Stores a value in a variable.	x = 5
Display	Shows output to the user.	DISPLAY "Hello"
Input	Gets data from the user.	INPUT name
If/Else	Executes different blocks of code based on a condition.	IF age >= 18 THEN DISPLAY "Eligible to vote" ELSE DISPLAY "Not eligible to vote" ENDIF
Loop (Repeat Until/While)	Repeats a block of code until a condition is met.	WHILE count < 10 DO DISPLAY count count = count + 1 ENDWHILE

3.2 Pseudocode Construction

1. Define the variables needed for the algorithm.
2. Write the steps of the algorithm in a clear and concise manner.
3. Use indentation to show the structure of the algorithm.
4. Use appropriate keywords to indicate control structures.

Example: Pseudocode for calculating the area of a rectangle.

START
  INPUT length
  INPUT width
  area = length * width
  DISPLAY "The area is: " + area
END