A tour of the top 5 sorting algorithms with Python code

George Seif
4 min readNov 26, 2018
Sorting algorithms complexities’

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Sorting is a skill that every software engineer and developer needs some knowledge of. Not only to pass coding interviews but as a general understanding of programming itself. The different sorting algorithms are a perfect showcase of how algorithm design can have such a strong effect on program complexity, speed, and efficiency.

Let’s take a tour of the top 6 sorting algorithms and see how we can implement them in Python!

Bubble Sort

Bubble sort is the one usually taught in introductory CS classes since it clearly demonstrates how sort works while being simple and easy to understand. Bubble sort steps through the list and compares adjacent pairs of elements. The elements are swapped if they are in the wrong order. The pass through the unsorted portion of the list is repeated until the list is sorted. Because Bubble sort repeatedly passes through the unsorted part of the list, it has a worst case complexity of O(n²).

Selection Sort

Selection sort is also quite simple but frequently outperforms bubble sort. If you are choosing between the two, it’s best to just default right to selection sort. With Selection sort, we divide our input list / array into two parts: the sublist of items already sorted and the sublist of items remaining to be sorted that make up the rest of the list. We first find the smallest element in the unsorted sublist and place it at the end of the sorted sublist. Thus, we are continuously grabbing the smallest unsorted element and placing it in sorted order in the sorted sublist. This process continues iteratively until the list is fully sorted.