Shell排序实现

Question

我理解Shell Sort背后的概念，但我发现下面的实现非常模糊和令人困惑。

public class Shell {
    public static void sort(Comparable[] a) { // Sort a[] into increasing order.
        int N = a.length;
        int h = 1;
        while (h < N / 3) h = 3 * h + 1; // 1, 4, 13, 40, 121, 364, 1093, ...
        while (h >= 1) { // h-sort the array.
            for (int i = h; i < N; i++) { // Insert a[i] among a[i-h], a[i-2*h], a[i-3*h]... .
                for (int j = i; j >= h && less(a[j], a[j - h]); j -= h)
                    exch(a, j, j - h);
            }
            h = h / 3;
        }
    }
}

请帮助我理解代码。

由于