Introduction to Coding Algorithms

Introduction to Algorithms

• Algorithm: A step-by-step set of instructions designed to solve a problem or perform a computation.

• Objective: Enables a solution to be expressed independently of programming languages, transforming specific user input into expected output.

Flowcharts and Pseudocode

• Flowchart: A visual representation of an algorithm using standardized symbols connected by directional arrows.

  • Start / End: Rounded rectangle or oval shape indicating program entry or exit.

  • Input / Output: Parallelogram shape for taking inputs or returning results.

  • Process: Rectangle shape for operations, calculations, or data assignments.

  • Decision: Diamond shape representing conditional questions that split execution paths into TRUE or FALSE.   

    

• Pseudocode: Short, structured, readable textual statements where each numbered step corresponds directly to a flowchart shape.

Variables and Constants

• Variable: A data element whose value can change during program execution (e.g., Height, Length, Age). A variable holds one value at a time.

• Constant: A fixed data item defined by the programmer whose value remains unchanged throughout program execution (e.g., Pi, number of letters in the alphabet).

Stages of an Algorithm

• Start: Initial step marking the start of execution (START).

• Input: Captures individual data inputs sequentially (e.g., Input $x$, Input $y$).

• Processing: Executes individual operations sequentially (e.g., $\text{Sum} \rightarrow x + y$, $\text{Product} \rightarrow x * y$).

• Output: Returns individual output values sequentially (e.g., Output Sum, Output Product).

• End: Final step concluding program execution (END).

Order of Instructions

• Sequence Sensitivity: The order of execution is critical when subsequent processes depend on prior outcomes.

• Mathematical Operations: Must strictly follow standard mathematical precedence rules such as BODMAS.

Decision Making and Logic

• Boolean Variable: A variable type limited to holding one of two possible values: True or False.

• Flowchart Decision: Uses a diamond shape containing a conditional query (e.g., $a > b?$). Path branching follows TRUE or FALSE arrows.   

  

• Pseudocode IF…THEN…ELSE Structure:

  • IF condition

  • THEN action if True

  • ELSE action if False

  • END IF

• Nested IF Statement: Used when evaluating three or more potential outcomes by embedding a secondary condition inside the ELSE block.