A-LevelComputer ScienceData StructuresMay/June 2025Paper 4 Q120 Marks
A program stores positive integers in a circular queue. The queue is stored as a global 1D array of 20 integers with the identifier Queue. Each index is initialised with the data -1 The global variable HeadPointer, initialised to -1, points to the first element in the queue. The global variable TailPointer, initialised to −1, points to the last element in the queue. The global variable NumberItems, initialised to 0, stores the number of items in the queue.
📋 Examiner Report & Trap Analysis
Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
🎯 Mark Scheme Breakdown
Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.
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