Quick Sort Algorithm: Divide-and-Conquer and Recursive Partitioning, Slides of Data Structures and Algorithms

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Presented

By :

Sallmaan

Hayat

Quick Sort

Course: Analysis & Design of Algorithms

Introduction

Quick Sort is a highly efficient divide-and-conquer sorting algorithm widely used in computer

science. This presentation explains its core concepts and demonstrates its implementation in

C++ using recursion. Understanding Quick Sort helps in optimizing sorting tasks with average

time complexity of O(n log n).

Key Concepts of Quick Sort

Key concepts include selecting a pivot, partitioning, and recursive sorting of sub-arrays. The

pivot choice affects performance. The algorithm continues recursively until base cases of one

or zero elements are reached, ensuring that the entire array is sorted efficiently.

Quick Sort

Implementation

in

C++

#include using namespace std; int partition(int arr[],int st, int end) { int j; int idx=st-1,pivot=arr[end], temp; for(j=st;j Detailed Pseudocode Walkthrough

The pseudocode begins by selecting a pivot and partitioning the array. Then, recursive calls are

made on the sub-arrays left and right of the pivot. Termination occurs when sub-array size is

less than two. This clear structure ensures easy implementation and maintenance.

Example and Step-by-Step Execution

Consider sorting the array [8, 4, 7, 3, 5]. Selecting a pivot, the array is partitioned, then

recursive calls sort the partitions. Each step reduces sub-array size, leading to a fully sorted

array. This example illustrates how recursion simplifies sorting.