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public class Shell {
    public static void sort(Comparable[] a) {
        // 将a[]按升序排列
        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) {
            for (int i = h; i < N; i++) {
                // a[j]<h-子数组中的前一个数就往前移
                for (int j = i; j >= h && less(a[j], a[j - h]); j = j - h) {
                    exch(a, j, j - h);
                }
            }
            h = h / 3;
        }
    }

    private static boolean less(Comparable v, Comparable w) {
        return v.compareTo(w) < 0;
    }

    private static void exch(Comparable[] a, int i, int j) {
        Comparable t = a[i];
        a[i] = a[j];
        a[j] = t;
    }

    private static void show(Comparable[] a) {
        for (int i = 0; i < a.length; i++) {
            System.out.print(a[i] + " ");
        }
        System.out.println();
    }

    public static void main(String[] args) {
        Integer[] a = {1, 3, 7, 7, 0, 5, 7, 1, 0, 5, 9};
        sort(a);
        show(a);
    }
}