quicksort-for-humans

int partition(vector<int>& a, int start, int end, int& comparisons, int& swaps)
{
    int pivot = a[end];
    int i = start;
    int j = start;
    while (i < end) {
        comparisons++;
        if (a[i] > pivot) {
            i++;
        }
        else {
            if (i != j) {
                swaps++;
                swap(&a[i], &a[j]);
            }
            i++;
            j++;
        }
    }
    if (i != j) {
        swaps++;
        swap(&a[i], &a[j]);
    }
    i++;
    j++;
    return j - 1;
}

void quickReq(vector<int>& a, int start, int end, int& comparisons, int& swaps)
{
    if (start < end)
    {
        int p = partition(a, start, end, comparisons, swaps);
        quickReq(a, start, p - 1, comparisons, swaps);
        quickReq(a, p + 1, end, comparisons, swaps);
    }
}

vector<int> QuickSort(vector<int> a, int& comparisons, int& swaps) {
    int n = a.size();
    comparisons = 0;
    swaps = 0;

    quickReq(a, 0, n-1, comparisons, swaps);

    return a;
}