Why does a recursive sorting algorithm need more memory than an iterative one?

Every unfinished recursive call keeps a stack frame holding its parameters and local variables. An iterative sort reuses one set of variables.

What is the trade-off between time and space in sorting?

An algorithm can often be made faster by using more memory, and smaller by accepting more time. The right balance depends on the machine and the data.

Which sorting algorithm would suit a device with only a few kilobytes of free memory?

Insertion sort suits a very small memory because it sorts in place with no recursion. Quicksort would need stack space that the device may not have.

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Data Structures: Arrays, Records and Hash Tables

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Sorting Algorithms

Topic overview Why a variety of sorting algorithms is needed Bubble sort Insertion sort Quicksort Comparisons, exchanges and passes Storage space and sorting efficiency Writing and altering sort algorithms

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Sorting Algorithms

Storage space and sorting efficiency

3 things to know
Component 1

Overview

Space complexity of a sorting algorithm, space complexity of bubble sort and insertion sort and space complexity of quicksort and explain where the space goes.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

What is meant by the space complexity of a sorting algorithm?

Key term

State the space complexity of bubble sort and insertion sort.

Key term

State the space complexity of quicksort and explain where the space goes.

Questions from this subtopic

Each one with the model answer underneath.

1
What is meant by the space complexity of a sorting algorithm?
Model answer
Space complexity describes how much extra memory the algorithm needs as the data grows. The measure excludes the storage of the original list.
2
State the space complexity of bubble sort and insertion sort.
Model answer
Bubble sort and insertion sort each have a space complexity of O(1). Only a single temporary variable is needed for a swap.
3
State the space complexity of quicksort and explain where the space goes.
Model answer
Quicksort uses O(log n) extra space on average. The space is the stack of frames for the unfinished recursive calls.
4
Why does a recursive sorting algorithm need more memory than an iterative one?
Model answer
Every unfinished recursive call keeps a stack frame holding its parameters and local variables. An iterative sort reuses one set of variables.
5
What is the trade-off between time and space in sorting?
Model answer
An algorithm can often be made faster by using more memory, and smaller by accepting more time. The right balance depends on the machine and the data.
6
Which sorting algorithm would suit a device with only a few kilobytes of free memory?
Model answer
Insertion sort suits a very small memory because it sorts in place with no recursion. Quicksort would need stack space that the device may not have.

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Data Structures: Arrays, Records and Hash Tables

Stacks, Queues, Linked Lists and Trees

Boolean Logic and Simplification

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