Algorithms, Decomposition & Abstraction
The Process: Abstraction is the act of removing or hiding unnecessary details that do not contribute to the solution of a specific problem. It allows the designer to focus solely on the important features required for implementation.
Modeling: Many computer systems are abstractions of real-world scenarios. For example, a flight simulator abstracts the physics of flight and cockpit controls but ignores the specific chemical composition of the jet fuel or the fabric texture of the seats.
Efficiency: By reducing complexity, abstraction saves memory and processing power. It ensures that the programmer does not waste resources on elements that have no impact on the final goal of the software.
The IPO Model: Every algorithm follows the Input-Process-Output model. Input is the data taken into the system; Process is the transformation or calculation performed on that data; and Output is the final result presented to the user.
Pseudocode: A text-based method of representing an algorithm using structured English. It is not a formal programming language but uses conventions like , , , and to describe logic clearly without worrying about strict syntax.
Flowcharts: A visual representation of an algorithm using standardized shapes. Ovals represent start/end points, rectangles represent processes, diamonds represent decisions, and parallelograms represent input/output.
| Concept | Primary Goal | Action Taken |
|---|---|---|
| Decomposition | Manageability | Breaking a whole into parts |
| Abstraction | Simplification | Filtering out irrelevant data |
| Algorithms | Execution | Creating a sequence of instructions |
Identify the 'Why': When asked about abstraction, always explain why a detail is being removed. For instance, if ignoring a player's hair color in a sports game, state that it has no impact on the game's mechanics or score tracking.
Trace Tables: Use trace tables to verify your algorithms. List every variable as a column and update their values line-by-line to ensure the logic reaches the expected output without errors.
Standard Symbols: In flowcharts, never mix up the shapes. Using a rectangle for a decision instead of a diamond is a common mistake that results in lost marks. Always ensure flow lines have arrows to indicate direction.