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OCR H446 1.4.2 Data Structures consolidation
Part 13 of 14 · H446 1.4.2 · Data structures
This is the mixed revision set for H446 1.4.2, so no new structures appear. Contexts are interleaved deliberately, which forces students to diagnose the behaviour a requirement needs before naming a structure, starting from a closed-book retrieval section and ending in an integrated game-server design.
Students will:
- recall structure choices from memory across contexts presented out of teaching order
- diagnose the required behaviour, such as indexed shape or ordered removal, before choosing a structure
- trace circular queue pointer updates and correct an unsafe linked-list insertion order
- compare a directed graph with a tree, and a binary search tree with a hash table, for stated purposes
- select and justify structures for six differing requirements in one game-server design
Inside: 4 explanation cells, 2 multiple-choice questions, 1 fill-in-the-blanks cell, 5 written answers and 1 trace table. 35 marks, about 60 to 75 minutes.
Series: H446 1.4.2 · Data structures, part 13 of 14.
Shared by Coding PathwayVerified teacher
- 13 cells
- About 60 minutes
- CC BY-SA 4.0
- Shared 31 Aug 2026
- Updated 3 Sept 2026
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The whole resource, exactly as a class sees it. Answers and marking are held back.
Data Structures consolidation
Complete the sections in order, beginning with closed-book retrieval and then applying the ideas in the integrated contexts. No new required knowledge is introduced.
This mixed set contains no new structures. First diagnose the required behaviour: indexed shape, named entity, LIFO/FIFO, links, network, hierarchy, ordered search or key lookup.
Retrieval model
Name the invariant before performing an operation. For pointer structures, draw state before/after. For selection, use operations and scenario consequences.
A parser must resolve the most recently opened unmatched bracket first. Which structure fits?
- AQueue
- BGraph
- CHash table
- DStack
One sensor reading has timestamp, numeric value and valid flag. Which structure best groups these named fields?
- ARecord
- B3D array
- CQueue
- DBST
Trace the circular pointer updates.
Enter a value only when it changes. Follow pointers and output in execution order.
Use one row for each pass through the loop. Fill in a box only when that value changes on that row, and leave the rest blank.
data = ["A", "B", "", ""]head = 0tail = 2count = 2for item in ["C", "D"]:data[tail] = itemtail = (tail + 1) % 4count = count + 1print(tail)print(count)
| Row | data | head | tail | count | item | Output |
|---|---|---|---|---|---|---|
| 1 | ||||||
| 2 | ||||||
| 3 | ||||||
| 4 | ||||||
| 5 | ||||||
| 6 |
A linked-list insertion performs previous.next = new before new.next is set. Explain the risk and give the safe update order.
Use orphan/reachability language.
Students type their answer here.
Compare a directed graph and a tree for modelling course prerequisites. State when each is suitable.
Use multiple parents, cycles and hierarchy.
Students type their answer here.
Compare a BST and hash table for exact student-ID lookup and sorted traversal.
Discuss both required operations and shape/collisions.
Students type their answer here.
Independent mixed design
A game server stores fixed 3D world cells, player records, undo history, incoming chat reports, friendships and ID lookup.
Choose one structure for each of the six requirements and justify four choices.
Use each structure’s behaviour/property.
Students type their answer here.
Choose three different structures from your design and describe one create/add, one traversal/search and one remove operation while preserving an invariant.
Name boundary cases.
Students type their answer here.
Final closed-book checkpoint
Complete each sentence from memory. There is no answer bank and correctness is held for teacher review.
Attempt DS14 only when you can perform an operation on each structure, not merely define it.