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Day 26

Day 26: Quicksort Algorithm

26/60 Days

Quicksort Algorithm #

Welcome to Day 26 of our 60 Days of Coding Algorithm Challenge! Today, we’ll dive deep into the Quicksort algorithm, one of the most efficient and widely used sorting algorithms in practice.

Introduction to Quicksort #

Quicksort is a divide-and-conquer algorithm that works by selecting a ‘pivot’ element from the array and partitioning the other elements into two sub-arrays, according to whether they are less than or greater than the pivot. The sub-arrays are then sorted recursively.

How Quicksort Works #

  1. Choose a pivot element from the array.
  2. Partition the array around the pivot, such that:
    • All elements less than the pivot are moved to its left.
    • All elements greater than the pivot are moved to its right.
  3. Recursively apply steps 1-2 to the sub-array of elements with smaller values and the sub-array of elements with greater values.

Basic Implementation of Quicksort #

Here’s a basic implementation of the Quicksort algorithm:

 1def quicksort(arr):
 2    if len(arr) <= 1:
 3        return arr
 4    else:
 5        pivot = arr[len(arr) // 2]
 6        left = [x for x in arr if x < pivot]
 7        middle …