排序--希尔排序

    public static void ShellSort(int[] arr)
    {
        int t;
        int j;
        int step = arr.length / 2;
        while(step >= 1)
        {
            for(int i = step; i < arr.length; i++)
            {
                if(arr[i] < arr[i - step])
                {
                    t = arr[i];
                    for(j = i - step; j >= 0 && arr[j] > t; j -= step)
                    {
                        arr[j + step] = arr[j];
                    }
                    arr[j + step] = t;
                }
            }
            step /= 2;
        }
    }