8.1.7

Merge Sort

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Merge Sort

Merge sort is an example of a divide and conquer algorithm, where the problem is broken down into smaller steps.

The concept

The concept

  • If we have two packs of cards, which are both already in order and want to combine them, what can we do?
  • One solution is to only consider the top card of each pile, and create a new deck starting from the smaller of the two cards.
  • This will give us a combined sorted pack.
  • This is called merge sort.
In English

In English

  • Split the lists into lists of size one.
  • Merge each pair of sublists by comparing the first value of each list and putting the smaller value into the new list first.
  • Continue merging until there is only one list.
Pros and cons of merge sort:

Pros and cons of merge sort:

  • Pros:
    • A very efficient algorithm.
  • Cons:
    • Can be slower for small lists.
    • Needs additional memory.
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Components of a Computer

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Databases

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Data Types

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Data Structures

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Boolean Algebra

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Algorithms

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Algorithms

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Practice questions on Merge Sort

Can you answer these? Test yourself with free interactive practice on Seneca — used by over 10 million students.

  1. 1
    When is it a particularly **bad** idea to use merge sort?Multiple choice
  2. 2
    Merge Sort in EnglishPut in order
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Insertion Sort

Search Algorithms