p23QuickSort.cpp

// 23.Write a program to sort list using quicksort. 
#include <iostream>
using namespace std;

// Partition function
int partition(int arr[], int low, int high) {
    int pivot = arr[high]; // Choosing the last element as pivot
    int i = low - 1;

    for (int j = low; j <= high - 1; j++) {
        // If current element is smaller than or equal to pivot
        if (arr[j] <= pivot) {
            i++; // Increment index
            swap(arr[i], arr[j]);
        }
    }

    swap(arr[i + 1], arr[high]);
    return (i + 1);
}

// QuickSort function
void quickSort(int arr[], int low, int high) {
    if (low < high) {
        // Partition the array
        int pi = partition(arr, low, high);

        // Recursively sort elements before and after partition
        quickSort(arr, low, pi - 1);
        quickSort(arr, pi + 1, high);
    }
}

// Print array
void printArray(int arr[], int size) {
    cout << "Sorted array: ";
    for (int i = 0; i < size; i++)
        cout << arr[i] << " ";
    cout << endl;
}

// Main function
int main() {
    int arr[] = {33, 10, 55, 71, 29, 3};
    int size = sizeof(arr) / sizeof(arr[0]);

    quickSort(arr, 0, size - 1);
    printArray(arr, size);

    cout << "\nProgram by ABHISHEK SINGH" << endl;
    cout << "Roll No: 2315272/2435222" << endl;

    return 0;
}