#include <iostream>

void quicksort(int a, int b, int arr[]);
void swap(int & a, int & b);


int main()
{
    int arr[7] = { 1, 7, 9, 2, 5, 10, 11, };
    quicksort(0, 6, arr);
    for (int i = 0; i < 6; i++)
        std::cout << arr[i] << " ";
    return 0;
}

void quicksort(int a, int b, int arr[])
{
    int i, j, piwot;
    i = (a + b) / 2;
    piwot = arr[i];
    arr[i] = arr[b];
    arr[b] = piwot;
    for (i = j = a; i < b; i++)
    {
        if (arr[i] < piwot)
        {
            swap(arr[i], arr[j]);
            j++;
        }
    }
    arr[b] = arr[j];
    arr[j] = piwot;
    if (a < j - 1) quicksort(a, j - 1, arr);
    if (b > j+ 1) quicksort(j + 1, b, arr);
}
void swap(int & a, int & b)
{
    int temp;
    temp = a;
    a = b;
    b = temp;
}