Insertion sort is a simple sorting algorithm that works similar to the way you sort playing cards in your hands. The array is virtually split into a sorted and an unsorted part. Values from the unsorted part are picked and placed at the correct position in the sorted part.

Characteristics of Insertion Sort:

• This algorithm is one of the simplest algorithm with simple implementation
• Basically, Insertion sort is efficient for small data values
• Insertion sort is adaptive in nature, i.e. it is appropriate for data sets which are already partially sorted.

Working of Insertion Sort algorithm:

Insertion Sort Algorithm

To sort an array of size N in ascending order:

• Iterate from arr[1] to arr[N] over the array.
• Compare the current element (key) to its predecessor.
• If the key element is smaller than its predecessor, compare it to the elements before. Move the greater elements one position up to make space for the swapped element.

Insertion Sort - Java Implementation

Insertion Sort - Python Implementation

Time Complexity: O(N^2) Auxiliary Space: O(1)

What are the Boundary Cases of Insertion Sort algorithm?

Insertion sort takes maximum time to sort if elements are sorted in reverse order. And it takes minimum time (Order of n) when elements are already sorted.

What are the Algorithmic Paradigm of Insertion Sort algorithm?

Insertion Sort algorithm follows incremental approach.

Is Insertion Sort an in-place sorting algorithm?

Yes, insertion sort is an in-place sorting algorithm.

Is Insertion Sort a stable algorithm?

Yes, insertion sort is a stable sorting algorithm.

When is the Insertion Sort algorithm used?

Insertion sort is used when number of elements is small. It can also be useful when input array is almost sorted, only few elements are misplaced in complete big array.

What is Binary Insertion Sort?

We can use binary search to reduce the number of comparisons in normal insertion sort. Binary Insertion Sort uses binary search to find the proper location to insert the selected item at each iteration. In normal insertion, sorting takes O(i) (at ith iteration) in worst case. We can reduce it to O(logi) by using binary search. The algorithm, as a whole, still has a running worst case running time of O(n^2) because of the series of swaps required for each insertion. Refer this for implementation.

How to implement Insertion Sort for Linked List?

Below is simple insertion sort algorithm for linked list.

• Create an empty sorted (or result) list
• Traverse the given list, do following for every node.
• Insert current node in sorted way in sorted or result list.
• Change head of given linked list to head of sorted (or result) list.

Reference:

https://www.geeksforgeeks.org/insertion-sort/?ref=lbp