评分标准模式

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Common MS Points for Sorting Algorithms

Bubble Sort (4–5 marks)

Point	Typical wording	Marks
Procedure/function header	FUNCTION bubbleSort(arr) RETURNS ARRAY	A1
Outer loop	FOR i ← 0 TO n-2 or FOR i ← 1 TO n-1	A1
Inner loop	FOR j ← 0 TO n-2-i	A1
Adjacent comparison	IF arr[j] > arr[j+1] — must be > for ascending	A1
Swap + return	Swap using temp variable; RETURN arr at end	A1

Insertion Sort — Iterative (4 marks)

Point	Typical wording	Marks
Loop from 1st element	FOR i ← 1 TO n-1 (do not start at 0)	A1
Store current item	curr ← arr[i] or key ← arr[i]	A1
While loop (shift)	WHILE j ≥ 0 AND arr[j] > curr — both conditions needed	A1
Insert	arr[j+1] ← curr after shifting	A1

Insertion Sort — Recursive (4 marks)

Point	Typical wording	Marks
Base case	IF n ≤ 1 THEN RETURN	A1
Recursive call	CALL insertionSortRec(arr, n-1)	A1
Shift loop	WHILE j ≥ 0 AND arr[j] > key	A1
Insert key	arr[j+1] ← key	A1

Generic MS Notes

• M marks (method) are awarded for correct structure / approach even if there are minor errors
• A marks (accuracy) require correct implementation — syntax errors lose A marks
• If a question says "write a procedure", do not use RETURN — use parameters by reference
• If a question says "write a function", a RETURN is required

Example MS — 9618/s24/qp/42 Q3 (Bubble Sort)

M1 Correct outer loop and inner loop structure (nested)
A1 Outer loop correct number of passes (n-1)
A1 Inner loop correct bound (n-1-i)
A1 Correct adjacent comparison (arr[j] > arr[j+1])
A1 Correct swap and return

Example MS — 9618/s24/qp/41 Q1d (Insertion Sort)

M1 Iterates from index 1 to last element
A1 Stores current element
A1 Shifting loop with correct conditions
A1 Inserts element at correct position