Algs4-2.1.27希尔排序的用时是次平方级的

2.1.27希尔排序的用时是次平方级的。在你的计算机上用SortCompare比较希尔排序和插入排序以及选择排序。测试数组的大小按照2的幂次递增，从128开始。
shell排序的倍率是2.5，选择和插入都是在4.
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public class SortCompare
{
    public static double time (String alg,Double[] a)
    {
        Stopwatch timer =new Stopwatch();
        if(alg.equals("Insertion")) Insertion.sort(a);
        //exercise2.1.24
        if(alg.equals("Insertion2")) Insertion2.sort(a);
        //exercise2.1.25
        if(alg.equals("Insertion3")) Insertion3.sort(a);
        //exercise2.1.26
        if(alg.equals("Insertion4")) Insertion3.sort(a);
        if(alg.equals("Selection")) Selection.sort(a);
        if(alg.equals("Shell")) Shell.sort(a);
       // if(alg.equals("Merge")) Merge.sort(a);
      //  if(alg.equals("Quick")) Quick.sort(a);
      //  if(alg.equals("Heap")) Heap.sort(a);
        return timer.elapsedTime();
    }
   
    public static double timeRandomInput(String alg,int N,int T)
    {
        double total =0.0;
        Double[] a=new Double[N];
        for (int t=0;t<T;t++)
        {
            for (int i=0;i<N;i++)
                a[i]=StdRandom.uniform();
            total+=time(alg,a);
        }
        return total;
    }//end timeRandomInput
   
   
    public static void main(String[] args)
    {
        /*
        String alg1=args[0];
        String alg2=args[1];
        int N=Integer.parseInt(args[2]);
        int T=Integer.parseInt(args[3]);
        double t1=timeRandomInput(alg1,N,T);
        double t2=timeRandomInput(alg2,N,T);
        StdOut.printf("For %d random Doubles %s is",N,alg1);
        StdOut.printf(" %.2f times faster than %s ",t2/t1,alg2);
        */
        double prevT1=0.0;
        double prevT2=0.0;
        double prevT3=0.0;
        double thisT1=0.0;
        double thisT2=0.0;
        double thisT3=0.0;
        for (int i=128;i<1000000;i=2*i)
        {
         prevT1=thisT1;
         prevT2=thisT2;
         prevT3=thisT3;
          //
         thisT1=timeRandomInput("Insertion",i,1);
         thisT2=timeRandomInput("Selection",i,1);
         thisT3=timeRandomInput("Shell",i,1);
         //
        StdOut.printf("---For %d random Doubles ",i);
        StdOut.printf("Insertion use time=%.2f ,tihisTime/prevTime=%.2f ",thisT1,thisT1/prevT1);
        StdOut.printf("Selection use time=%.2f ,tihisTime/prevTime=%.2f ",thisT2,thisT2/prevT2);
        StdOut.printf("Shell     use time=%.2f ,tihisTime/prevTime=%.2f ",thisT3,thisT3/prevT3);
        }
    }
   
}

public class Insertion
{
    public static void sort(Comparable[] a)
    {
        int N=a.length;
        for (int i=0;i<N;i++)
        {
            for(int j=i;j>0 && less(a[j],a[j-1]);j--)
                exch(a,j,j-1);
        }
    }
   
    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;
    }
   
     public static void main(String[] args)
    {
        int N=Integer.parseInt(args[0]);
        Double[] a=new Double[N];
        for(int i=0;i<N;i++)
            a[i]=StdRandom.uniform(0.0,N*1.0);
        //
        sort(a);
    }
}


public class Selection
{
    public static void sort(Comparable[] a)
    {
        int N=a.length;
        for (int i=0;i<N;i++)
        {
            int min=i;
            for (int j=i+1;j<N;j++)
                if (less(a[j],a[min])) min=j;
            exch(a,i,min);
            //showAnimation(a);
        }
    }
   

    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();
    }
   
   
    private static void showAnimation(Comparable[] a)
    {
       StdDraw.setXscale(0.0,a.length);
       StdDraw.setYscale(0.0,a.length);
       StdDraw.setPenRadius(0.005);
       StdDraw.pause(100);
       StdDraw.clear(StdDraw.GRAY);
       StdDraw.setPenColor(StdDraw.BLACK);
        for(int i=0;i<a.length;i++)
        {
            StdDraw.line(i*1.0,0.0,i*1.0,(Double)a[i]*1.0);
        }
    }
    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;
    }
   
    public static void main(String[] args)
    {
        int N=Integer.parseInt(args[0]);
        Double[] a=new Double[N];
        for(int i=0;i<N;i++)
            a[i]=StdRandom.uniform(0.0,N*1.0);
        //
        StdDraw.pause(5000);
        sort(a);
    }
}


public class Shell
{
    public static int timesOfCompare;
    public static int timesOfCompareTotal;
    public static void sort(Comparable[] a)
    {
        int N=a.length;
        int h=1;
        while (h<N/3) h=3*h+1;
        while (h>=1)
        {
            for (int i=h;i<N;i++)
            {
             for (int j=i;j>=h && less(a[j],a[j-h]);j-=h)
             { 
                 timesOfCompare++;
                 exch(a,j,j-h);
             }
            }
          /* if (h>1)
         {
            StdOut.printf(" sort-%d ",h);
                        for(int l=0;l<N;l++)
                        {
                            if (l%h==0) StdOut.println();
                            StdOut.printf("%3d",a[l]);
                        }
           }
           */
            h=h/3;
        }
    }
    //sort40
    public static void sort40(Comparable[] a)
    {
        int N=a.length;
        int h=40;
        for (int i=h;i<N;i++)
            {
              for (int j=i;j>=h;j-=h)
                   { 
                     timesOfCompare++;
                     timesOfCompareTotal++;
                    // StdOut.printf("timesOfCompare=%d ,i=%d ,j=%d ,j-h=%d ",timesOfCompare,i,j,j-h);
                     if (less(a[j],a[j-h])) 
                         exch(a,j,j-h);
                     else
                         break;
                   }
            }
      
        /* StdOut.printf(" sort-%d ",h);
         for(int l=0;l<N;l++)
              {
                if (l%h==0) StdOut.println();
                StdOut.printf("%3d",a[l]);
              }
          */
    }
    //sort13
    public static void sort13(Comparable[] a)
    {
        int N=a.length;
        int h=13;
        for (int i=h;i<N;i++)
            {
              for (int j=i;j>=h;j-=h)
                   { 
                     timesOfCompare++;
                     timesOfCompareTotal++;
                     if (less(a[j],a[j-h])) 
                         exch(a,j,j-h);
                     else
                         break;
                   }
            }
        /*
        StdOut.printf(" sort-%d ",h);
         for(int l=0;l<N;l++)
              {
                if (l%h==0) StdOut.println();
                StdOut.printf("%3d",a[l]);
              }
              */
    }
    //sort4
    public static void sort4(Comparable[] a)
    {
        int N=a.length;
        int h=4;
        for (int i=h;i<N;i++)
            {
              for (int j=i;j>=h;j-=h)
                   { 
                     timesOfCompare++;
                     timesOfCompareTotal++;
                     if (less(a[j],a[j-h]))
                         exch(a,j,j-h);
                     else
                         break;
                   }
            }
        /*
        StdOut.printf(" sort-%d ",h);
         for(int l=0;l<N;l++)
              {
                if (l%h==0) StdOut.println();
                StdOut.printf("%3d",a[l]);
              }
              */
    }
    //sort1
    public static void sort1(Comparable[] a)
    {
        int N=a.length;
        int h=1;
        for (int i=h;i<N;i++)
            {
              for (int j=i;j>=h;j-=h)
                   { 
                     timesOfCompare++;
                     timesOfCompareTotal++;
                     if (less(a[j],a[j-h]))
                         exch(a,j,j-h);
                     else
                         break;
                   }
            }
        /*
        StdOut.printf(" sort-%d ",h);
         for(int l=0;l<N;l++)
              {
                if (l%h==0) StdOut.println();
                StdOut.printf("%3d",a[l]);
              }
              */
    }
     
   
    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;
    }
   
    public static void main(String[] args)
    {
   
        //worst sort13
        Integer[] worst13={100,92,84,76,68,60,52,44,36,28,21,14,7,99,91,83,75,67,59,51,43,35,27,20,13,6,98,90,82,74,66,58,50,42,34,26,19,12,5,97,89,81,73,65,57,49,41,33,25,18,11,4,96,88,80,72,64,56,48,40,32,24,17,10,3,95,87,79,71,63,55,47,39,31,23,16,9,2,94,86,78,70,62,54,46,38,30,22,15,8,1,93,85,77,69,61,53,45,37,29};
        timesOfCompareTotal=0;
        timesOfCompare=0;
        sort40(worst13);
        StdOut.printf("worst13 sort40 timesOfCompare=%4d timesOfCompareTotal=%4d " , timesOfCompare,timesOfCompareTotal);

       timesOfCompare=0;
       sort13(worst13);
       StdOut.printf("worst13 sort13 timesOfCompare=%4d timesOfCompareTotal=%4d " , timesOfCompare,timesOfCompareTotal);
      
        timesOfCompare=0;
        sort4(worst13);
        StdOut.printf("worst13  sort4 timesOfCompare=%4d timesOfCompareTotal=%4d " , timesOfCompare,timesOfCompareTotal);
      
        timesOfCompare=0;
        sort1(worst13);
        StdOut.printf("worst13  sort1 timesOfCompare=%4d timesOfCompareTotal=%4d " , timesOfCompare,timesOfCompareTotal);
        StdOut.println("------------------------------");

          
     

        String[] files={
            "a40-13-4.txt","a40-4-13.txt","a13-4-40.txt","a13-40-4.txt","a4-40-13.txt","a4-13-40.txt",
            "b40-13-4.txt","b40-4-13.txt","b13-4-40.txt","b13-40-4.txt","b4-40-13.txt","b4-13-40.txt",
            "c40-13-4.txt","c40-4-13.txt","c13-4-40.txt","c13-40-4.txt","c4-40-13.txt","c4-13-40.txt",
            "d-big-small.txt","asc.txt"
        };
        for(int f=0;f<files.length;f++)
        {
        int[] a=In.readInts(files[f]);
        Integer[] worst=new Integer[a.length];
        for(int i=0;i<a.length;i++)
            worst[i]=a[i];
        timesOfCompareTotal=0;
        timesOfCompare=0;
        sort40(worst);
        StdOut.println("---"+files[f]+"---");
        StdOut.printf("sort40 timesOfCompare=%4d timesOfCompareTotal=%4d " , timesOfCompare,timesOfCompareTotal);

        timesOfCompare=0;
        sort13(worst);
        StdOut.printf("sort13 timesOfCompare=%4d timesOfCompareTotal=%4d " , timesOfCompare,timesOfCompareTotal);
      
        timesOfCompare=0;
        sort4(worst);
        StdOut.printf("sort4 timesOfCompare=%4d timesOfCompareTotal=%4d " , timesOfCompare,timesOfCompareTotal);
      
        timesOfCompare=0;
        sort1(worst);
        StdOut.printf("sort1 timesOfCompare=%4d timesOfCompareTotal=%4d " , timesOfCompare,timesOfCompareTotal);
        StdOut.println("");
        }
    }    

  
}
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原文地址：https://www.cnblogs.com/longjin2018/p/9860053.html