Hill sort study notes

public class SortDemo2 {
    public static void main(String[] args) {
        int[] a = creatInt2();

        shellSort(a);

    }

    // 正序
    private static int[] creatInt() {
        int[] a = new int[10000001];
        for (int i = 0; i < 10000001; i++) {
            a[i] = i;
        }
        return a;
        // 100001  开始时间:1525767016491,结束时间:1525767016530,用了多长时间:39
        //10000001开始时间:1525768053766,结束时间:1525768055427,用了多长时间:1661
    }

    // 反序
    private static int[] creatInt2() {
        int[] a = new int[10000001];
        for (int i = 10000000, j = 0; j < 10000001; i--, j++) {
            a[j] = i;
        }
        return a;
        // 100001 开始时间:1525767003666,结束时间:1525767003708,用了多长时间:42
        //10000001 开始时间:1525768094010,结束时间:1525768096270,用了多长时间:2260
    }

    // 希尔排序
    public static void shellSort(int[] a) {
        Date d = new Date();
        long start = d.getTime();
        int j;
        for (int gap = a.length / 2; gap > 0; gap /= 2) {//要排序的hk   a[i]<=a[i+hk]
            for (int i = gap; i < a.length; i++) {
                Integer temp = a[i];
                for (j = i; j >= gap && temp.compareTo(a[j - gap]) < 0; j -= gap)//如果a[i]<a[i-hk] ===a[i]>a[i+hk]
                    a[j] = a[j - gap];
                a[j] = temp;
            }

        }

        /*for (int i : a) {
            System.out.print(i + ",");
        }
        System.out.println();*/

        Date d2 = new Date();
        long end = d2.getTime();
        System.out.println("开始时间:" + start + ",结束时间:" + end + ",用了多长时间:" + (end - start));

    }
}