void quickSort(vector <student> &list, long left, long right)
{
    long l = left;
    long r = right;
    string middle = list[(left + right) / 2].subname;

    while (l <= r)
    {
        while (list[l].subname < middle)
            l++;
        while (list[r].subname > middle)
            r--;

        if (l <= r)
        {
            swap(list[l], list[r]);
            l++;
            r--;
        }
    }

    if (left < r)
        quickSort(list, left, r);
    if (l < right)
        quickSort(list, l, right);
}


void heapify(vector <student> &list, long size, long i)
{
    long left = 2 * i + 1;
    long right = 2 * i + 2;
    long largest = i;

    if (left < size && list[left].subname > list[largest].subname)
        largest = left;
    if (right < size && list[right].subname > list[largest].subname)
        largest = right;

    if (largest != i)
    {
        swap(list[i], list[largest]);
        heapify(list, size, largest);
    }
}

void buildHeap(vector <student> &list, long size)
{
    for (long i = size / 2 - 1; i != -1; i--)
        heapify(list, size, i);
}

void heapSort(vector <student> &list)
{
    buildHeap(list, list.size());
    for (long i = list.size() - 1; i > 0; i--)
    {
        swap(list[0], list[i]);
        heapify(list, i, 0);
    }
}