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评分标准模式

General Mark Allocation Rules​

MarkTypeMeaning
M1Method mark设对结构/算法即得，即使有小错
A1Accuracy mark依赖前面的 M1，实现完全正确
B1Independent mark独立给分，不依赖其他步骤
E1Explanation mark解释正确，通常出现在论述题

Pattern 1: Declare + Initialize (3 marks)​

分配逻辑

M1 — Correct DECLARE with 2D array syntax and correct bounds

A1 — Outer FOR loop for rows with correct range

A1 — Inner FOR loop for columns with assignment arr[i][j] ← value

Common MS note: "If bounds are reversed (row/column swapped), penalise once only."

Pattern 2: Read Data From File Into 2D Array (5 marks)​

分配逻辑

M1 — Open file / file reading structure

A1 — Nested loop for rows

A1 — Nested loop for columns

A1 — Correct file read and store into arr[i][j]

A1 — Close file after reading

Pattern 3: Insertion Sort by Column (5 marks)​

分配逻辑

M1 — Outer loop i starting at 2

A1 — Store entire current row as key

A1 — Compare arr[j][col] with key[col]

A1 — Shift rows: arr[j+1] ← arr[j]

A1 — Insert key row at correct position

Common MS note: "Comparing the wrong column loses A1." "Partial sort (only sorting one column values instead of full rows) loses A1."

Pattern 4: Binary Tree Insert Into 2D Array (8 marks)​

分配逻辑

M1 — Find / track next free row

A1 — Insert data into free row

A1 — Set LeftPointer ← -1, RightPointer ← -1

M1 — Check if tree empty (root = -1)

A1 — Correct root assignment for empty case

A1 — Traverse left/right based on comparison

A1 — Update parent's pointer when inserting

A1 — Loop / recursion terminates correctly

Pattern 5: Binary Tree Traversal (4 marks)​

分配逻辑

M1 — Recursive procedure with index parameter

A1 — Base case check (index = -1)

A1 — Recursive call left, output, recursive call right (in correct order for in-order)

A1 — Correct array column access for left/data/right

Key MS Observations From Past Papers​

  • A simple syntax error (e.g. NEXT missing variable) usually does not lose the mark — intent matters
  • Reversed loop bounds (e.g. 1 TO 0) loses the mark
  • Array indices out of bounds at runtime loses the accuracy mark
  • Using a 1D array instead of 2D loses all method marks
  • For binary tree questions: forgetting to set -1 for new node's pointers typically loses A1
  • For sort questions: using bubble sort instead of insertion sort is not penalised unless the question specifies insertion sort