Overview of Abstract Data Types (ADTs) in VCE Algorithmics

The ADT Landscape

VCE Algorithmics (HESS) covers a core set of ADTs, each suited to different problem types. They can be grouped into:

KEY TAKEAWAY: Choosing the right ADT is the core skill. Each ADT has operations that match certain problem patterns — match the ADT’s capabilities to the problem’s requirements.

Choosing the Right ADT

Use this decision framework when facing a problem:

1. Do order and duplicates matter? → List or Array
2. Is membership/uniqueness important? → Set
3. Do you need key-based lookup? → Dictionary
4. LIFO access (undo, backtracking)? → Stack
5. FIFO access (scheduling, BFS)? → Queue
6. Priority-based access? → Priority Queue
7. Relationships between entities? → Graph
8. Hierarchical/decision structure? → Tree / Decision Tree

Combining ADTs

Many real-world problems require combinations:
- A graph whose nodes contain dictionaries (e.g., city with attributes)
- A priority queue of lists (e.g., job batches ordered by urgency)
- A dictionary mapping strings to sets (e.g., word → set of documents)

VCAA FOCUS: Exam questions frequently test whether students can select and justify an appropriate ADT or combination of ADTs for a described real-world scenario.

Summary Table