Computational thinking and Problem-solving: past paper questions

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• Question 7May/June 2026, paper 31Structured9 marks

  Write this infix expression in Reverse Polish Notation (RPN).

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• Question 9Oct/Nov 2025, paper 31Structured9 marks

  A stack has been implemented using pseudocode to store a maximum of 100 string items using the global variables in the following table: Identifier | Data type…

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• Question 11Oct/Nov 2024, paper 31Structured12 marksHas a diagram

  The following diagram shows an ordered binary tree. A linked list of nodes is used to store the data. Each node consists of a left pointer, the data and a right pointer.

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• Question 9Oct/Nov 2023, paper 31Structured9 marks

  Write the infix expression for this Reverse Polish Notation (RPN) expression: 5 2 – 5 4 + * 9 /

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• Question 9May/June 2026, paper 31Structured9 marksHas a diagram

  Explain how supervised learning and unsupervised learning are trained.

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• Question 12Oct/Nov 2025, paper 32Structured9 marks

  A stack has been implemented using pseudocode to store a maximum of 100 string items using the global variables in the following table: Identifier Data type…

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• Question 11Oct/Nov 2024, paper 32Structured12 marksHas a diagram

  This binary tree shows an ordered list of integers. A linked list of nodes is used to store the data. Each node consists of a left pointer, the data and a right pointer.

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• Question 10Oct/Nov 2023, paper 31Structured10 marks

  A stack is to be set up using the information in the table.

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• Question 10May/June 2026, paper 31Structured9 marks

  An insertion sort algorithm is used to sort the unique ID numbers of club members into ascending order. These unique ID numbers are kept in a 1D array MemberID. The corresponding names of the members are stored in a 1D array Names.

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• Question 8Oct/Nov 2025, paper 33Structured5 marksHas a diagram

  Calculate the shortest distance between the Start node and each of the nodes in the graph using Dijkstra’s algorithm.

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• Question 8Oct/Nov 2023, paper 32Structured5 marksHas a diagram

  Calculate the shortest distance between the Start and each of the destinations in the diagram using Dijkstra’s algorithm.

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• Question 11Oct/Nov 2025, paper 33Structured3 marks

  Describe when the use of recursion would be beneficial and give an example.

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• Question 1Oct/Nov 2024, paper 41Structured22 marks

  A program sorts string data using different sorting methods. The text file Data.txt stores string data items. Each data item is on a new line in the text file.

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• Question 9Oct/Nov 2023, paper 32Structured13 marks

  A stack Abstract Data Type (ADT) is to be implemented using pseudocode, with procedures to initialise it and to push new items onto the stack. A 1D array Stack stores the contents of the stack.

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• Question 9May/June 2026, paper 32Structured9 marksHas a diagram

  State the subset of Artificial Intelligence (AI) which makes use of an artificial neural network.

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• Question 1Oct/Nov 2025, paper 41Structured20 marks

  A program stores integers in a stack. The stack is represented as a 1D array of 30 elements with the identifier Stack The global pointer TopOfStack stores the index of the last element inserted into the stack.

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• Question 3Oct/Nov 2024, paper 41Structured19 marks

  A linked list stores positive integer data in a 2D array. The first dimension of the array stores the integer data. The second dimension of the array stores the pointer to the next node in the linked list.

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• Question 10May/June 2026, paper 32Structured9 marks

  Two examples of searching algorithms are a linear search and a binary search. Describe how increasing the number of data items in the file to be searched affects the time efficiency of these search algorithms.

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• Question 3Oct/Nov 2025, paper 41Structured25 marks

  A program stores records in the 2D array HashTable. Each record is stored at a specific index of the array that is calculated using a hashing algorithm with the record’s key field. The array has 100 × 10 elements.

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• Question 3Oct/Nov 2024, paper 42Structured17 marks

  The text file HighScoreTable.txt stores the top seven player scores for a game. The data in the file is stored in the order: Player ID Game level Score Each item of data is stored on a new line.

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• Question 7May/June 2026, paper 33Structured9 marks

  Outline the process of using a stack to evaluate an expression written using Reverse Polish Notation (RPN).

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• Question 2Oct/Nov 2025, paper 42Structured26 marks

  A program stores 20 unique random integers between 0 and 100 (inclusive) in a 1D array that is local to the main program. Write program code to declare the array local to the main program and store 20 unique random numbers between 0 and 100 (inclusive) in the array.

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• Question 1Oct/Nov 2023, paper 41Structured16 marks

  This iterative pseudocode algorithm for the function IterativeVowels() takes a string as a parameter and counts the number of lower-case vowels in this string.

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• Question 9May/June 2026, paper 33Structured8 marksHas a diagram

  Explain what is meant by regression methods in relation to machine learning.

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• Question 3Oct/Nov 2025, paper 42Structured21 marks

  A program stores integers in ascending order in an ordered binary tree. The tree is implemented as a 2D array. Each node is stored with three values: • a pointer to the left node • the data • a pointer to the right node.

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• Question 2Oct/Nov 2023, paper 42Structured17 marks

  An integer is said to be divisible by another integer if the result of the division is also an integer.

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• Question 10May/June 2026, paper 33Structured9 marks

  A program declares a 1D array globally as PartName[1:1000000] OF STRING, and sorts its contents in ascending alphabetical order. The function PartSearch performs a binary search on the array. The item to be found is passed as a parameter.

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• Question 3Oct/Nov 2025, paper 43Structured20 marks

  A program is written to perform different individual processes using arrays. (a) A 1D array stores 10 integers.

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• Question 5May/June 2024, paper 31Structured9 marksHas a diagram

  Write this Reverse Polish Notation (RPN) in infix form: 5 2 + 9 3 - / 3 *

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• Question 1May/June 2026, paper 42Structured18 marks

  A program stores nine lower-case strings in a 1D array TheData. The following strings are stored in the order shown: laptop tablet printer computer processor monitor memory cable touchscreen Write program code to declare the array TheData in the main program.

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