A-LevelComputer ScienceAlgorithms and Data StructuresMay/June 2022Paper 2 Q510 Marks
Study the following pseudocode. Line numbers are for reference only. 10 PROCEDURE Encode () 11 DECLARE CountA, CountB, ThisNum : INTEGER 12 DECLARE ThisChar : CHAR 13 DECLARE Flag : BOOLEAN 14 CountA ← 0 15 CountB ← 10 16 Flag ← TRUE 17 INPUT ThisNum 18 WHILE ThisNum <> 0 19 ThisChar ← LEFT(NUM_TO_STR(ThisNum), 1) 20 IF Flag = TRUE THEN 21 CASE OF ThisChar 22 '1' : CountA ← CountA + 1 23 '2' : IF CountB < 10 THEN 24 CountA ← CountA + 1 25 ENDIF 26 '3' : CountB ← CountB – 1 27 '4' : CountB ← CountB – 1 28 Flag ← FALSE 29 OTHERWISE : OUTPUT "Ignored" 30 ENDCASE 31 ELSE 32 IF CountA > 2 THEN 33 Flag ← NOT Flag 34 OUTPUT "Flip" 35 ELSE 36 CountA ← 4 37 ENDIF 38 ENDIF 39 INPUT ThisNum 40 ENDWHILE 41 OUTPUT CountA 42 ENDPROCEDURE
📋 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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