C# 归并排序性能

只是简单说明一下，这不是家庭作业。我只是想温习我的算法。我正在使用 C# 中的 MergeSort，并且编写了一个可以基于泛型进行排序的递归方法：

class SortAlgorithms
{

    public T[] MergeSort<T> (T[] unsortedArray) where T : System.IComparable<T>
    {
        T[] left, right;
        int middle = unsortedArray.Length / 2;

        left = new T[middle];
        right = new T[unsortedArray.Length - middle];

        if (unsortedArray.Length <= 1)
            return unsortedArray;

        for (int i = 0; i < middle; i++)
        {
            left[i] = unsortedArray[i];
        }

        for (int i = middle; i < unsortedArray.Length; i++)
        {
            right[i - middle] = unsortedArray[i];
        }

        left = MergeSort(left);

        right = MergeSort(right);


        return Merge<T>(left, right);
    }

    private T[] Merge<T> (T[] left, T[] right) where T : System.IComparable<T>
    {
        T[] result = new T[left.Length + right.Length];

        int currentElement = 0;

        while (left.Length > 0 || right.Length > 0)
        {
            if (left.Length > 0 && right.Length > 0)
            {
                if (left[0].CompareTo(right[0]) < 0)
                {
                    result[currentElement] = left[0];
                    left = left.Skip(1).ToArray();
                    currentElement++;
                }
                else
                {
                    result[currentElement] = right[0];
                    right = right.Skip(1).ToArray();
                    currentElement++;
                }
            }
            else if (left.Length > 0)
            {
                result[currentElement] = left[0];
                left = left.Skip(1).ToArray();
                currentElement++;
            }
            else if (right.Length > 0)
            {
                result[currentElement] = right[0];
                right = right.Skip(1).ToArray();
                currentElement++;
            }
        }

        return result;
    }
}

这可行，但速度慢得令人痛苦。我使用 System.Diagnostic.StopWatch 来检查 Array.Sort（使用 QuickSort 算法）的性能，以与我的 MergeSort 进行比较，差异如此之大，我想知道我是否实施了错误。任何意见？

我不是一名 C# 程序员，但问题可能出在使用这样的语句吗？

left = left.Skip(1).ToArray();

This might be implemented in a way that forces a deep copy of the underlying array. If so, this would drop the performance of merge from O(n) to O(n²), immediately dropping the performance of the resulting merge sort from O(n log n) to O(n²).

（这是因为重复率从

T(1) = O(1)

T(n) ≤ 2T(n / 2) + O(n)

有解 T(n) = O(n log n)，

T(1) = O(1)

T(n) ≤ 2T(n / 2) + O(n²)

which has solution T(n) = O(n²).)