Algs4-2.1.30几何级数递增序列

2.1.30几何级数递增序列。通过实验找到一个t,使得对于大小为N=10^6的任意随机数组，使用递增序列1,下取整(t),下取整(t^2),
下取整（t^3),下取整(t^4),...的希尔排序的运行时间最短。给出你能找到的三个最佳t值以及相应的递增序列。
t=5.31,递增序列：28    149    795    4221    22416    119031    632056
t=5.39,递增序列：29    156    844    4549    24520    132166    712377
t=4.01,递增序列：16    64    258    1036    4157    16672    66858    268101
public class E2d1d30
{
    public static void main(String[] args)
    {
        int[] SN=new int[20];
        int h;
        int i;
        int maxSN=1000000;
        int tLength=10000;
        Double[][] tAndTime=new Double[tLength][2];
        int indexOftAndTime=0;
        //
        int N=1000000;
        int minValue=0;
        int maxValue=1000000;
        Integer[] a=new Integer[N];
        Integer[] aCopy=new Integer[N];
        for(int j=0;j<N;j++)
        {
            a[j]=StdRandom.uniform(minValue,maxValue);
            aCopy[j]=a[j];
        }
        //
        for(double t=3.3;t<10.0;t=t+0.01)
        {
            i=0;
            h=1;
            SN[i]=h;
            i=1;
            for(double k=2.0;k<10.0 && i<20;k++)
            {
                h=(int)Math.floor(Math.pow(t,k));
                if (h<maxSN)
                    SN[i]=h;
                else
                    break;
                i++;
            }//end for k 
         //
         Stopwatch timer =new Stopwatch();
         Shell2.sort(a,SN);
         tAndTime[indexOftAndTime][0]=t;
         tAndTime[indexOftAndTime][1]=timer.elapsedTime();        
         indexOftAndTime++;
         //
         for(int j=0;j<N;j++)
         a[j]=aCopy[j];
        }//end for t
        //
        for(int j=0;tAndTime[j][0]>0&&j<tLength;j++)
            StdOut.printf("%f\t%f\n",tAndTime[j][0],tAndTime[j][1]);
           
    }
}

public class Shell2
{
    public static void sort(Comparable[] a,int[] SN)
    {
        int N=a.length;
        int h;
        for (int hIndex=SN.length-1;hIndex>0;hIndex--)
        {
            h=SN[hIndex];
            for (int i=h;i<N;i++)
            {
                for (int j=i;j>=h && less(a[j],a[j-h]);j-=h)
                    exch(a,j,j-h);
            }
        }
    }
   
    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++)
            StdOut.print(a[i]+" ");
        StdOut.println();
    }
   
    public static boolean isSorted(Comparable[] a)
    {
        for (int i=0;i<a.length;i++)
            if(less(a[i],a[i-1])) return false;
        return true;
    }
}