Copiuta

int pivot(int a[], int first, int last)
{
    int  p=first;
    int pivotElement=a[first];

    for(int i=first+1;i<=last;i++)
    {
        if(a[i]<=pivotElement)
        {
            p++;
            swap(a[i],a[p]);
        }
    }

    swap(a[p],a[first]);

    return p;
}

void quickSort(int a[],int first,int last)
{
    int pivotElement;

    if(first<last)
    {
        pivotElement = pivot(a, first, last);
        quickSort(a, first, pivotElement-1);
        quickSort(a, pivotElement+1, last);
    }
}