题型分析

Question Type 1: Array Declaration and Initialization (1–2 marks)

How to identify: The question asks you to declare an array and fill it with initial values. Usually appears as the first part of a larger question.

Standard Method:

• Use list multiplication [0] * N for 1D
• Use nested list comprehension for 2D
• Match the data type required (integer, string, etc.)

MS Pattern:

• M1 for correct declaration with correct size
• A1 for correct initial values

Example 1 — source:

A program needs to store the temperatures for 7 days. Write program code to declare and initialise an array Temperatures with 7 elements, each set to 0.

MS Expand

• M1 declaration with size 7: Temperatures = [0] * 7
• A1 all elements set to 0

Example 2 — source:

Declare a 2D array Grid with 5 rows and 6 columns, initialised to 0.

MS Expand

• M1 correct nested list comprehension syntax
• A1 dimensions 5 rows × 6 columns, all 0

Common traps:

• Using [0] * 5 for a 2D array (creates shallow copies)
• Wrong order of rows and columns
• Not using global when declaration is inside a function

---

Question Type 2: Reading Data into an Array (4–6 marks)

How to identify: You are given a data source (user input, file, or generated values) and must store values into an array using a loop.

Standard Method:

1. Declare the array (if not already done)
2. Use a for loop with range()
3. Inside the loop, assign each element:
   • User input: Array[i] = int(input(...))
   • File: Array[i] = int(File.readline())
4. Handle validation if required

MS Pattern:

• M1 correct loop structure with range()
• M2 read/accept a value inside loop
• A1 store value at correct index
• B1 correct data type conversion

Example 1 — source:

Write program code that asks the user to enter 10 scores and stores them in an array Scores.

MS Expand

Scores = [0] * 10
for i in range(10):
    Scores[i] = int(input("Enter score: "))

• M1 array declaration Scores = [0] * 10
• M2 loop for i in range(10)
• A1 assign input to Scores[i]
• B1 use of int() for type conversion

Example 2 — source:

Read 20 integers from a text file data.txt into an array Numbers. Each integer is on a separate line.

MS Expand

Numbers = [0] * 20
File = open("data.txt", "r")
for i in range(20):
    Numbers[i] = int(File.readline())
File.close()

• M1 open file and declare array
• M2 loop for i in range(20)
• A1 File.readline() and int() conversion
• B1 close file

Common traps:

• Forgetting int() conversion for numeric data
• Off-by-one: using range(1, 11) with 0-based array
• Not pre-allocating array before assigning by index
• Forgetting global if inside a function

---

Question Type 3: Array Traversal and Processing (2–4 marks)

How to identify: You must iterate over an existing array to perform a calculation (sum, average, count, find max/min, search).

Standard Method:

1. Declare accumulator variables (sum, count, max, etc.)
2. Loop through all elements using for i in range(len(Array))
3. Apply processing logic inside the loop
4. Output or return the result

MS Pattern:

• M1 correct loop structure
• M2 correct accumulation / comparison logic
• A1 correct final result

Example 1 — source:

The array Marks contains 30 integer values. Write program code to calculate and output the total of all values in Marks.

MS Expand

Total = 0
for i in range(len(Marks)):
    Total = Total + Marks[i]
print(Total)

• M1 loop for i in range(len(Marks))
• M2 accumulation Total = Total + Marks[i]
• A1 output Total

Example 2 — source:

The array Temperatures contains 365 values. Write program code to find and output the highest value in the array.

MS Expand

Max = Temperatures[0]
for i in range(1, len(Temperatures)):
    if Temperatures[i] > Max:
        Max = Temperatures[i]
print(Max)

• M1 initialise Max to first element
• M2 loop through remaining elements with comparison
• A1 update Max when larger value found and output

Common traps:

• Initialising max to 0 instead of first element (fails if all values negative)
• Off-by-one in loop range
• Using Total =+ Marks[i] instead of Total += Marks[i]
• Not using len() when array size varies