Practise 38 real questions on Algorithm design and problem solving from 2021 to 2026. See the answer and explanation as soon as you answer.
Algorithm design and problem solving is one of the 4 main topics in our O Level Computer Science (Cambridge (CAIE) 2210) question bank, and about 19% of its real questions come from it. Tayyari Karo has 38 real questions on this topic from 2021 to 2026, from Paper 2. By difficulty: 27 medium, 9 easy, 2 hard.
Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.
These are real past-paper questions. Think of your answer first, then open the explanation.
Tick one box to identify the type of validation check to test whether a number entered into a computer system is between two set values: A length check; B presence check; C type check; D range check. [1]
D (range check).
A range check tests whether a value lies between two limits.
2 Identify three different types of test data that can be used to test a program.
2 normal (typical valid data), boundary (at the limits of valid input), erroneous (invalid data that should be rejected).
Tick one box to complete this sentence. A validation check to make sure that an email address contains an '@' sign is a: A range check; B visual check; C presence check; D format check.
D - format check (it checks the data is in the correct format / pattern).
Checking for '@' is a format check.
1 Tick one box to show which check is used for verification when data is input: length check, range check, type check, visual check.
1 visual check
State two features that should be included to create a maintainable program. Give a reason why each feature should be used.
Any two, e.g.:
1. Meaningful variable/identifier names - makes the code easier to read and understand so future changes are simpler.
2. Comments - explain what sections of code do, helping programmers maintain/debug it.
(Other valid: indentation for readability; modular structure using procedures/functions.)
Maintainable: meaningful names + comments + indentation + modularity.
5 The first stage of the program development life cycle is analysis. Two tasks in analysis are abstraction and decomposition.
(a) Describe what is meant by abstraction.
(b) Identify three of the component parts when a problem has been decomposed at the analysis stage.
(c) Identify and describe one other stage of the program development life cycle.
5 (a) Abstraction is removing unnecessary detail and focusing only on the essential information needed to solve the problem.
(b) Three component parts when decomposed: inputs required; processes/calculations to be carried out; outputs produced (or sub-problems/modules).
(c) One other stage, e.g. design (planning how the program will work, e.g. flowcharts/structure charts); coding/implementation (writing the program); testing (checking it works); maintenance (fixing/updating after release).
Give one piece of normal test data and one piece of erroneous test data that could be used to validate the input of an email address. State the reason for your choice in each case.
Normal test data: e.g. "student@example.com" - it is a valid email containing an @ symbol and a domain, so it should be accepted.
Erroneous test data: e.g. "studentexample.com" (no @ symbol) - it is missing the @ symbol so it should be rejected by the validation.
(Other valid: erroneous = "student@" missing domain.)
Normal = valid format accepted; erroneous = invalid format rejected.
3 A PIN is input into a banking app. Before acceptance: check 1 - each character must be a digit; check 2 - exactly four digits; check 3 - value between 1000 and 9999 inclusive.
(a) Describe each validation check.
(b) The PIN can be changed by the user. Describe how the new PIN could be verified before use.
3 (a) Check 1: check that every character of the PIN is numeric (0-9); reject if any character is not a digit. Check 2: check the length of the PIN is exactly 4 characters. Check 3: range check that the numeric value is >= 1000 and <= 9999.
(b) Verification: the user is asked to enter the new PIN twice and the two entries are compared; if they match it is accepted (or the input is displayed back for the user to confirm it is correct).
| Session | Paper 2 |
|---|---|
| May/June 2026 | 4 |
| May/June 2025 | 4 |
| Oct/Nov 2025 | 4 |
| May/June 2024 | 3 |
| Oct/Nov 2024 | 3 |
| May/June 2023 | 5 |
| Oct/Nov 2023 | 2 |
| May/June 2022 | 3 |
| Oct/Nov 2022 | 4 |
| May/June 2021 | 2 |
| Oct/Nov 2021 | 4 |
38 real O Level Computer Science (2210) questions on Algorithm design and problem solving from 2021 to 2026, from Paper 2. Each one shows the year, session and paper it came from.
Yes. Every question shows the correct answer and a short explanation the moment you answer.
You can start free with no signup. A small set of papers per subject is free, and Premium unlocks every paper, the full question bank and the paper PDFs.
