Quicksort Doubly LinkedList - 不显示排名第一

Question

我正在为双重链接列表实现快速排序。

我已尝试过这篇文章的解决方案： QuickSort on Doubly Linked List

代码有效，但如果我有类似的东西：

129 149 169 3 7000 20 5000

它返回： 20 129 149 169 5000 7000

它是排序的，但第一个值在哪里？

我正在使用此代码：

public DoublyLinkedList quicksort(DoublyLinkedList in, int numOfElements) {
    in.first = partition(in.first, in.first.prev);
    return in;
}

private ListElement partition(ListElement first, ListElement pivotElement) {
    ListElement left = first;
    ListElement right = pivotElement;

    while (left != pivotElement) {
        if (left.getKey() > pivotElement.getKey()) {
            ListElement next = left.next;
            if (left == first)
                first = next;
            //Remove currentLeft
            left.prev.next = left.next;
            left.next.prev = left.prev;

            //Connect with element after currentRight
            left.next = right.next;
            right.next.prev = left;

            //Connect with pivotElement
            left.prev = right;
            right.next = left;

            right = left; //Switch right with left, since we just swapped their positions
            left = next;  //Assign left to the next object (from the left part)
        } else {
            left = left.next;
        }
    }
    if (first != pivotElement.prev && first != pivotElement)
        first = partition(first, pivotElement.prev);
    if (pivotElement != right)
        partition(pivotElement.next, right);
    return first;
}