Deep Dive: Merge Sort

Part of Binary Search · Section 6 of 9

Study NotesUnit: 3.1 Fundamentals of AlgorithmsGCSE

This study notes covers Deep Dive: Merge Sort within Binary Search for GCSE Computer Science. Revise Binary Search in 3.1 Fundamentals of Algorithms for GCSE Computer Science with 15 exam-style questions and 10 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 6 of 9 in this topic. Use this study notes to connect the idea to the wider topic before moving on to questions and flashcards.

Deep Dive: Merge Sort

Divide and conquer:

  1. Divide: Split list in half until single elements
  2. Conquer: Merge pairs back together in sorted order

[38, 27, 43, 3] → [38, 27] and [43, 3] → [38] [27] [43] [3] → [27, 38] [3, 43] → [3, 27, 38, 43]

Uses more memory (creates new arrays) but much faster for large lists!

Practice questions for Binary Search

Which of the following is a requirement before binary search can be used?

  • A. The list must contain an even number of items
  • B. The list must be sorted in order
  • C. The list must be stored in a 2D array
  • D. The target value must be in the first half of the list
1 markfoundation

Describe how a binary search algorithm finds a target value in a sorted list.

3 marksstandard

Quick recall flashcards

What is the time complexity of binary search?
O(log n) - logarithmic time
What technique does binary search use?
Divide and conquer - repeatedly halves the search space

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