TheAlgorithms-C-Plus-Plus/sorting/quick_sort.cpp

/* C implementation QuickSort */
#include <iostream>
using namespace std;

int partition(int arr[], int low, int high)
{
    int pivot = arr[high]; // pivot
    int i = (low - 1);     // Index of smaller element

    for (int j = low; j < high; j++)
    {
        // If current element is smaller than or
        // equal to pivot
        if (arr[j] <= pivot)
        {
            i++; // increment index of smaller element
            int temp = arr[i];
            arr[i] = arr[j];
            arr[j] = temp;
        }
    }
    int temp = arr[i + 1];
    arr[i + 1] = arr[high];
    arr[high] = temp;
    return (i + 1);
}

void quickSort(int arr[], int low, int high)
{
    if (low < high)
    {

        int p = partition(arr, low, high);

        quickSort(arr, low, p - 1);
        quickSort(arr, p + 1, high);
    }
}

void show(int arr[], int size)
{
    for (int i = 0; i < size; i++)
        cout << arr[i] << "\n";
}

// Driver program to test above functions
int main()
{
    int size;
    cout << "\nEnter the number of elements : ";

    cin >> size;

    int arr[size];

    cout << "\nEnter the unsorted elements : ";

    for (int i = 0; i < size; ++i)
    {
        cout << "\n";
        cin >> arr[i];
    }
    quickSort(arr, 0, size);
    cout << "Sorted array\n";
    show(arr, size);
    return 0;
}