Insertion Sort vs. Selection Sort: Know the Difference
By Shumaila Saeed || Published on February 22, 2024
Insertion Sort builds a sorted list by repeatedly inserting unsorted elements at their correct positions, whereas Selection Sort finds the smallest element and places it at the beginning, repeating for all elements.
Key Differences
Insertion Sort works by taking one element from the unsorted part and finding its correct position in the sorted part, effectively building the sorted array incrementally. In contrast, Selection Sort repeatedly finds the minimum element from the unsorted part and places it at the end of the sorted part.
Shumaila Saeed
Feb 22, 2024
Insertion Sort is efficient for small data sets and partially sorted arrays, as it has fewer operations in such scenarios. Selection Sort, however, does not have a performance advantage with partially sorted data and performs a fixed number of comparisons regardless of the initial order of the elements.
Shumaila Saeed
Feb 22, 2024
In Insertion Sort, the array is virtually split into a sorted and an unsorted part, and elements are picked from the unsorted part and moved to their correct position in the sorted part. Selection Sort also divides the array into sorted and unsorted parts but works by selecting the smallest (or largest) element from the unsorted part and swapping it with the first element of the unsorted part.
Shumaila Saeed
Feb 22, 2024
Insertion Sort typically performs better than Selection Sort in terms of the number of swaps made, making it preferable when write operations are a costly operation. Selection Sort, on the other hand, makes O(n) swaps in the worst case, which is minimal compared to other sorting algorithms.
Shumaila Saeed
Feb 22, 2024
The algorithmic complexity of both Insertion Sort and Selection Sort in the worst case is O(n^2), where n is the number of elements. However, the average-case complexity of Insertion Sort can be better than Selection Sort, especially for nearly sorted arrays.
Shumaila Saeed
Feb 22, 2024
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Comparison Chart
Basic Operation
Inserts an element into its correct position.
Selects the smallest element and swaps it.
Shumaila Saeed
Feb 22, 2024
Best for
Small or partially sorted data sets.
Data sets where the cost of swaps is not an issue.
Shumaila Saeed
Feb 22, 2024
Complexity
O(n^2) in the worst case; better in average cases.
O(n^2) regardless of the initial order of elements.
Shumaila Saeed
Feb 22, 2024
Number of Swaps
Fewer swaps, especially for nearly sorted arrays.
Fixed number of swaps, O(n) in the worst case.
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Feb 22, 2024
Performance Characteristic
Adapts to the existing order of elements.
Constant performance irrespective of initial order.
Shumaila Saeed
Feb 22, 2024
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Insertion Sort and Selection Sort Definitions
Insertion Sort
Insertion Sort iteratively sorts by expanding the sorted section of the array.
Insertion Sort progressively organized the array, one element at a time.
Shumaila Saeed
Jan 23, 2024
Selection Sort
A sorting algorithm that selects the smallest element and places it at the beginning.
Selection Sort systematically found the lowest value to sort the array.
Shumaila Saeed
Jan 23, 2024
Insertion Sort
A sorting method where each new element is placed into the correct sorted position.
With Insertion Sort, the programmer efficiently managed the incremental data additions.
Shumaila Saeed
Jan 23, 2024
Selection Sort
An algorithm dividing the array into sorted and unsorted regions, and sorting by selection.
She used Selection Sort for its simplicity in sorting numerical data.
Shumaila Saeed
Jan 23, 2024
Insertion Sort
A sorting algorithm that builds the final sorted array one item at a time.
Insertion Sort quickly sorted the nearly ordered list of customer names.
Shumaila Saeed
Jan 23, 2024
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Selection Sort
Selection Sort improves sorting by minimizing the number of swaps.
To minimize write operations, Selection Sort was the algorithm of choice.
Shumaila Saeed
Jan 23, 2024
Insertion Sort
An algorithm that sorts by inserting elements into their correct position.
For her small dataset, she chose Insertion Sort for its efficiency.
Shumaila Saeed
Jan 23, 2024
Selection Sort
A straightforward sorting method performing a fixed number of comparisons.
In his coding challenge, he implemented Selection Sort for its predictable behavior.
Shumaila Saeed
Jan 23, 2024
Insertion Sort
A simple sorting technique effective for small and partially sorted arrays.
He used Insertion Sort to reorder the slightly shuffled deck of cards.
Shumaila Saeed
Jan 23, 2024
Selection Sort
A sorting technique where the next smallest element is repeatedly placed in the sorted sequence.
With Selection Sort, each pass secured the next smallest number in the sequence.
Shumaila Saeed
Jan 23, 2024
Repeatedly Asked Queries
What is Selection Sort?
A sorting algorithm that repeatedly selects the smallest element from the unsorted part and places it at the beginning of the sorted part.
Shumaila Saeed
Feb 22, 2024
Is Selection Sort good for large datasets?
Not typically, as its performance is O(n^2) regardless of data size.
Shumaila Saeed
Feb 22, 2024
How does Insertion Sort handle nearly sorted arrays?
It performs well, often with fewer iterations and swaps.
Shumaila Saeed
Feb 22, 2024
What is Insertion Sort?
A sorting algorithm that builds a sorted array by inserting each element into its correct position.
Shumaila Saeed
Feb 22, 2024
Can Selection Sort be used on partially sorted arrays?
Yes, but it doesn’t offer a performance advantage in this case.
Shumaila Saeed
Feb 22, 2024
Which algorithm is easier to understand?
Selection Sort is often considered simpler to understand.
Shumaila Saeed
Feb 22, 2024
Does Insertion Sort require many swaps?
It generally requires fewer swaps, especially for nearly sorted data.
Shumaila Saeed
Feb 22, 2024
Are these algorithms stable?
Insertion Sort is stable, but Selection Sort is not.
Shumaila Saeed
Feb 22, 2024
How do they compare in terms of auxiliary space?
Both require minimal auxiliary space, generally O(1).
Shumaila Saeed
Feb 22, 2024
How does Insertion Sort work for small datasets?
It is efficient for small datasets as it has fewer operations.
Shumaila Saeed
Feb 22, 2024
What is the swap frequency in Selection Sort?
It makes a fixed number of swaps, O(n) in the worst case.
Shumaila Saeed
Feb 22, 2024
Is Selection Sort suitable for data that is constantly being added?
Not particularly, as it does not adapt well to incremental data.
Shumaila Saeed
Feb 22, 2024
Does the initial order matter for Selection Sort?
No, it performs consistently regardless of the initial order.
Shumaila Saeed
Feb 22, 2024
What is the worst-case complexity for both algorithms?
Both have a worst-case complexity of O(n^2).
Shumaila Saeed
Feb 22, 2024
Can Insertion Sort be used in real-time systems?
Yes, especially since it's efficient for small or streaming data.
Shumaila Saeed
Feb 22, 2024
How does the initial order of data affect Insertion Sort?
Its performance improves with the initial order of data.
Shumaila Saeed
Feb 22, 2024
Which is faster, Insertion Sort or Selection Sort?
Insertion Sort is generally faster, especially for smaller or nearly sorted arrays.
Shumaila Saeed
Feb 22, 2024
Are these sorting algorithms suitable for educational purposes?
Yes, both are commonly used for teaching basic sorting concepts.
Shumaila Saeed
Feb 22, 2024
Which sort is better for write-intensive operations?
Insertion Sort, due to fewer swaps.
Shumaila Saeed
Feb 22, 2024
Do these algorithms work well with large data sets?
Not ideally, as their time complexity is quadratic.
Shumaila Saeed
Feb 22, 2024
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About Author
Written by
Shumaila SaeedShumaila Saeed, an expert content creator with 6 years of experience, specializes in distilling complex topics into easily digestible comparisons, shining a light on the nuances that both inform and educate readers with clarity and accuracy.
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