# Insertion Sort vs. Selection Sort: What's the Difference?

Edited by Huma Saeed || By Sawaira Riaz || Published on February 2, 2024
Insertion sort builds a sorted array one item at a time, while selection sort repeatedly finds the minimum element and moves it to the sorted portion.

## Key Differences

Insertion sort works by dividing the array into a sorted and an unsorted region. It iteratively takes an element from the unsorted part and inserts it into its correct position in the sorted part. On the other hand, selection sort divides the array similarly but works by repeatedly finding the smallest (or largest) element from the unsorted portion and moving it to the end of the sorted portion. Each iteration selects an item and puts it in its final position.
Sawaira Riaz
Feb 02, 2024
In insertion sort, the sorted section grows one element at a time, and elements are moved only within this section to accommodate the new element. This process is akin to the way one might sort a hand of playing cards. Conversely, selection sort does not guarantee that the sorted section remains sorted after each iteration, as it always looks for the smallest element in the unsorted section regardless of the current order.
Huma Saeed
Feb 02, 2024
Insertion sort is adaptive; it can perform well on a partially sorted array, often requiring fewer steps. It is efficient for small datasets and can be more efficient than selection sort in certain scenarios. However, selection sort performs the same number of comparisons regardless of the initial order of the elements. It's not adaptive and has a consistent performance, but it generally performs less efficiently than insertion sort.
Sawaira Riaz
Feb 02, 2024
The complexity of insertion sort in the worst case is O(n^2), where n is the number of elements. However, its average and best-case performance is better, especially for partially sorted arrays. Selection sort also has a complexity of O(n^2) for all cases, as it always performs n(n-1)/2 comparisons and n swaps in total, making it generally slower and less efficient than insertion sort for larger arrays.
Sawaira Riaz
Feb 02, 2024
Insertion sort is more efficient and faster for smaller lists, where the overhead of more complex algorithms doesn’t justify their use. It also works well for data sets that are already mostly sorted. Selection sort, while simple and easy to understand, does not have these adaptive characteristics, making it less suitable for large datasets or ones that are already partially sorted.
Sawaira Riaz
Feb 02, 2024

## Comparison Chart

### Sorting Method

Inserts each element in its proper place
Selects the minimum and swaps it with the first unsorted element
Sawaira Riaz
Feb 02, 2024

### Performance on Small Data

Efficient for small or partially sorted arrays
Less efficient than insertion sort
Sawaira Riaz
Feb 02, 2024

### Complexity

O(n^2) in the worst case, but can be faster for partially sorted data
Consistently O(n^2) regardless of initial order
Sawaira Riaz
Feb 02, 2024

Adaptive, performance varies based on initial order
Sawaira Riaz
Feb 02, 2024

Faster for small or nearly sorted data
Simplicity and ease of implementation
Sawaira Riaz
Feb 02, 2024

### Swapping Operations

Fewer swaps as it only rearranges within the sorted part
Swaps every time it finds the minimum element
Sawaira Riaz
Feb 02, 2024

## Insertion Sort and Selection Sort Definitions

#### Insertion Sort

Involves fewer movements, making it efficient for smaller or nearly sorted data.
Insertion sort was the ideal choice due to the minimal rearrangements needed.
Sawaira Riaz
Jan 22, 2024

#### Selection Sort

A sorting algorithm that selects the smallest (or largest) element and moves it to the sorted section.
Selection sort methodically found and placed the smallest element at the beginning.
Sawaira Riaz
Jan 22, 2024

#### Insertion Sort

Efficient for small datasets and simple to implement.
For our small contact list, we used insertion sort for its efficiency.
Janet White
Jan 22, 2024

#### Selection Sort

Divides the array into two parts: sorted and unsorted, working by swapping elements.
In each iteration, selection sort added the next smallest number to the sorted part.
Sawaira Riaz
Jan 22, 2024

#### Insertion Sort

A sorting algorithm that builds the final sorted array one item at a time.
Insertion sort efficiently organized the nearly sorted list of student names.
Sawaira Riaz
Jan 22, 2024

#### Selection Sort

Performs a fixed number of comparisons, with complexity always being O(n^2).
Selection sort was less efficient for the large dataset due to its quadratic complexity.
Harlon Moss
Jan 22, 2024

#### Insertion Sort

Works by dividing the array into sorted and unsorted parts.
Using insertion sort, each number was placed in its correct position iteratively.
Huma Saeed
Jan 22, 2024

#### Selection Sort

Non-adaptive, with consistent performance regardless of the initial array order.
Selection sort consistently performed with the same efficiency, irrespective of the data’s initial order.
Sawaira Riaz
Jan 22, 2024

#### Insertion Sort

Adapts to the existing order of elements, performing well on partially sorted arrays.
Insertion sort quickly handled the partially ordered dataset.
Sawaira Riaz
Jan 22, 2024

#### Selection Sort

Simple and easy to implement, but less efficient for larger lists.
We used selection sort for its simplicity in our basic programming tutorial.
Aimie Carlson
Jan 22, 2024

## FAQs

#### What is insertion sort?

A sorting algorithm that builds the sorted array one element at a time.
Sawaira Riaz
Feb 02, 2024

#### What is selection sort?

A sorting method that repeatedly finds the minimum element and adds it to the sorted portion.
Huma Saeed
Feb 02, 2024

#### Can selection sort be more efficient for large datasets?

No, it's generally less efficient for larger datasets compared to more advanced algorithms.
Sawaira Riaz
Feb 02, 2024

#### How does insertion sort differ from selection sort in performance?

Insertion sort is generally faster for small or partially sorted data, while selection sort has consistent performance regardless of data order.
Sawaira Riaz
Feb 02, 2024

#### How does selection sort handle unsorted data?

It consistently performs the same number of comparisons regardless of the data's initial state.
Harlon Moss
Feb 02, 2024

#### Is insertion sort easy to implement?

Yes, it's straightforward and efficient for small datasets.
Sawaira Riaz
Feb 02, 2024

#### Can insertion sort be used in real-time applications?

Yes, especially where data is continuously added and needs to be sorted.
Aimie Carlson
Feb 02, 2024

Yes, its performance varies based on the initial order of data.
Harlon Moss
Feb 02, 2024

#### What is the time complexity of insertion sort?

Its worst-case complexity is O(n^2), but it can be faster for partially sorted data.
Harlon Moss
Feb 02, 2024

#### How many swaps does insertion sort make?

It makes fewer swaps, as it only rearranges within the sorted section.
Sawaira Riaz
Feb 02, 2024

#### How does insertion sort compare to more complex algorithms?

It's simpler and more efficient for small datasets, but less so for larger ones.
Aimie Carlson
Feb 02, 2024

#### What are the disadvantages of insertion sort?

It becomes inefficient as the size of the dataset increases.
Aimie Carlson
Feb 02, 2024

#### Does selection sort require more memory?

No, it sorts in place and does not require additional memory.
Sawaira Riaz
Feb 02, 2024

#### What type of data is selection sort not good for?

It's not ideal for large or complex datasets due to its quadratic complexity.
Harlon Moss
Feb 02, 2024

#### Is selection sort stable?

No, it's not stable as it may change the relative order of equal elements.
Sawaira Riaz
Feb 02, 2024

#### Does selection sort work well with duplicate elements?

Yes, it can sort arrays with duplicates, but it's not stable.
Harlon Moss
Feb 02, 2024

#### Can selection sort be optimized for better performance?

Basic optimizations can be made, but it generally remains O(n^2) in complexity.
Janet White
Feb 02, 2024

#### Which sort is better for nearly sorted data?

Insertion sort is typically better for nearly sorted data.
Aimie Carlson
Feb 02, 2024

#### Are there any variants of insertion sort?

Yes, variants like binary insertion sort improve the basic algorithm.
Janet White
Feb 02, 2024

#### Is selection sort suitable for educational purposes?

Yes, due to its simplicity, it's often used for teaching sorting algorithms.
Sawaira Riaz
Feb 02, 2024