IB Computer Science HL · Year 2 · Lesson 27
Sets as ADTs
Abstract data types separate what operations mean from how they are implemented, helping you choose structures by behaviour and trade-offs.
Paper 250 minutesB4.1.5
Use Next or the arrow keys.
Today’s targets
What you need to be able to do
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- Construct + applyAnd apply sets as an ADT
B4.1.5
Paper 2 lensMatch the depth of every response to the command term. Previously learned content can move quickly, but retrieval must still be accurate.
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Retrieve
Rapid Recall Deck
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Say the answer aloud before flipping. Mark secure knowledge quickly and spend time on the gaps.
- What two characteristics define a set ADT?: Elements are unique and the set is unordered.
- What does the union of two sets contain?: Every element that appears in either set, with no duplicates.
- What does the intersection of two sets contain?: Only elements present in both sets.
- What does the difference A − B contain?: Elements that are in A but not in B.
- What do subset and superset describe?: A is a subset of B if every element of A is in B; B is then a superset of A.
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B4.1.5 · Learn
Core knowledge and application
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B4.1.5Construct + apply
And apply sets as an ADT
Abstract data types separate what operations mean from how they are implemented, helping you choose structures by behaviour and trade-offs.
Exam moveBuild the structure/solution and use it correctly in a new context.
Required detail 1The fundamental characteristics of sets, including their unordered nature and the uniqueness of elements
Required detail 2Operations: union, intersection and difference
Required detail 3Code to check if an element is in a set, to add an element to a set, to remove an element, and to check whether one set is a subset/superset of another set
Assessment boundaryPaper 2
Explain it without notes
Construct + apply: And apply sets as an ADT in the context of a system that needs efficient insertion, search and set membership.
- The fundamental characteristics of sets, including their unordered nature and the uniqueness of elements
- Operations: union, intersection and difference
- Code to check if an element is in a set, to add an element to a set, to remove an element, and to check whether one set is a subset/superset of another set
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Trace / construct
Programming checkpoint
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a = {1, 2, 3}
b = {3, 4}
print(a | b) # union
print(a & b) # intersection
print(a - b) # differenceSet<Integer> a = new HashSet<>(Arrays.asList(1,2,3)); Set<Integer> b = new HashSet<>(Arrays.asList(3,4)); Set<Integer> union = new HashSet<>(a); union.addAll(b);
Before you run itTrace the code by hand. Identify state changes, branch/loop behaviour, and the final result.
Modify it
Change one condition, input or operation so the program solves a slightly different problem. Predict the effect before editing.
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Apply
Transfer to a new scenario
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ScenarioA system that needs efficient insertion, search and set membership needs a design or technical decision related to today’s topic. Explain what matters and why.
- The fundamental characteristics of sets, including their unordered nature and the uniqueness of elements
- Operations: union, intersection and difference
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Exam lens
Paper 2 practice
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Build the response before checking notesUse precise terminology and match the required depth.
- Construct + apply: And apply sets as an ADT in the context of a system that needs efficient insertion, search and set membership.
Self-checkAnswer the exact command term. For explain, include mechanism/reason; for compare, pair criteria; for discuss/evaluate/justify, build supported reasoning and a conclusion.
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Homework
Finish the learning cycle
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IA — main task
Continue Criterion D development. Keep code readable, record meaningful implementation decisions, and maintain testing/evidence notes as you work.
Syllabus — short
Complete one targeted Paper 2/Paper 1 retrieval task from today’s lesson.
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End of Lesson 27.