c++ Quick Sort (random pivot)

gistfile1.cpp

#include <iostream>
#include <stdlib.h>

void quick_sort(int *list, int p, int r);

int main(int argc, char const *argv[])
{
    int n = 11;
    int list[n];
    srand(time(NULL));

    std::cout << "Before sorting." << std::endl;
    for (int i = 0; i < n; i++)
    {
        list[i] = rand() % 300;
        std::cout << list[i] << ", ";
    }
    std::cout << std::endl;

    int pivot_key = rand() % n;
    int pivot = list[pivot_key];
    list[pivot_key] = list[n - 1];
    list[n - 1] = pivot;

    std::cout << "Before sorting. After changing the pivot." << std::endl;
    for (int i = 0; i < n; i++)
    {
        std::cout << list[i] << ", ";
    }
    std::cout << std::endl;

    quick_sort(list, 0, n - 1);

    std::cout << "After sorting." << std::endl;
    for (int j = 0; j < n; j++)
    {
        std::cout << list[j] << ", ";
    }
    std::cout << std::endl;
    return 0;
}

void quick_sort(int *list, int p, int r)
{
    if (p < r)
    {
        int q = p;
        int temp_key;
        for (int u = p; u < r; ++u)
        {
            if (list[u] <= list[r])
            {
                temp_key = list[q];
                list[q] = list[u];
                list[u] = temp_key;
                q++;    
            }
        }
        temp_key = list[q];
        list[q] = list[r];
        list[r] = temp_key;
        quick_sort(list, p, q - 1);
        quick_sort(list, q + 1, r);
    }
}