Python: Insertion sort

Last update on April 23 2025 12:50:18 (UTC/GMT +8 hours)

6. Insertion Sort

Write a Python program to sort a list of elements using the insertion sort algorithm.
Note: According to Wikipedia "Insertion sort is a simple sorting algorithm that builds the final sorted array (or list) one item at a time. It is much less efficient on large lists than more advanced algorithms such as quicksort, heapsort, or merge sort."

Pictorial Presentation: Insertion Sort

Python: Insertion sort

Sample Solution:

Python Code:

def insertionSort(nlist):
   for index in range(1,len(nlist)):

     currentvalue = nlist[index]
     position = index

     while position>0 and nlist[position-1]>currentvalue:
         nlist[position]=nlist[position-1]
         position = position-1

     nlist[position]=currentvalue

nlist = [14,46,43,27,57,41,45,21,70]
insertionSort(nlist)
print(nlist)

Sample Output:

[14, 21, 27, 41, 43, 45, 46, 57, 70]

Flowchart :

For more Practice: Solve these Related Problems:

Write a Python program to implement insertion sort and display the list after inserting each element.
Write a Python script to sort a list of strings using insertion sort and then print the sorted list.
Write a Python program to use insertion sort to sort a list of numbers and count the number of shifts required.
Write a Python function to perform insertion sort on a list of floating-point numbers and then verify the sorted order.

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