Learning objective

Binary search: Know and be able to trace and analyse the time complexity of the binary search algorithm. Time complexity is O(log n).

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Searching algorithms

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Binary search

Aqa A Level Computer ScienceFundamentals of algorithms

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Binary search: Know and be able to trace and analyse the time complexity of the binary search algorithm. Time complexity is O(log n)

This point belongs to Searching algorithms, especially Binary search.
You need to be able to binary search: Know and be able to trace and analyse the time complexity of the binary search algorithm. Time complexity is O(log n).
Use the linked flashcards and practice questions to check recall, then practise applying the idea in an exam-style answer.

Why it matters

This objective helps connect Binary search to exam-style questions, flashcards, and revision notes for Searching algorithms.

Quick student answer

A binary search is performed on the sorted list [3, 7, 11, 15, 19, 23, 27] to find 23. Using the middle item of the current search range, which items are checked?

Direct answer

15, then 23

Key terms

Binary search: A search algorithm that repeatedly checks the middle of an ordered range and discards the half that cannot contain the target.
Time complexity: A description of how the number of operations performed by an algorithm changes as the input size increases.

Common trap

Using binary search on unordered data: Ensure the data is ordered first, because binary search relies on the order to decide which half to discard.

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Question 1

A binary search is performed on the sorted list [3, 7, 11, 15, 19, 23, 27] to find 23. Using the middle item of the current search range, which items are checked?

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Binary search: Know and be able to trace and analyse the time complexity of the binary search algorithm. Time complexity is O(log n).

Understand this objective

Binary search: Know and be able to trace and analyse the time complexity of the binary search algorithm. Time complexity is O(log n)

A binary search is performed on the sorted list [3, 7, 11, 15, 19, 23, 27] to find 23. Using the middle item of the current search range, which items are checked?

Try this as a practice card

A binary search is performed on the sorted list [3, 7, 11, 15, 19, 23, 27] to find 23. Using the middle item of the current search range, which items are checked?

Flip through the key recall cards

Choose how to practise

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