Re: Szybkość Javy wg Horstmanna a testy...

Article View: pl.comp.lang.java

Article #141790

#141790

From: jarekr
Date: Mon, 20 Oct 2008 13:25

64 lines
2555 bytes

No to już, żeby zakończyć dyskusje
wersja na 15ms
 (nie używa bitset)
public class TestCode5
{

   public static void main(String[] s)
   {
      int n = 2000000;
      for (int i = 0 ; i < 10000; i++)
      {
    	  doAllCalculations(100);
      }
      for (int i = 0 ; i < 10; i++)
      {
    	  doAllCalculations(n);
      }
      doItForMe(n);
   }

private static void doItForMe(int n)
{
	long start = System.currentTimeMillis();
      int count = doAllCalculations(n);
      long end =  System.currentTimeMillis();
  	System.out.println("Ilosc: " + count);
	System.out.println((end - start) + " ms.");
}

private static int doAllCalculations(int n)
{
	boolean[] b = new boolean[n+1];
      int count = 0;
      int i;
      for (i = 2; i <= n; i++)
         b[i] = true;
      i = 2;
      while (i * i <= n)
      {
         if (b[i])
         {

            count++;
            int k = 2 * i;
            while (k <= n)
            {
               b[k]=false;
               k += i;
            }
         }
         i++;
      }
      while (i <= n)
      {
         if (b[i])
         {

            count++;
         }
         i++;
      }
	return count;
}
}

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From: jarekr <jratajski@gmail.com>
Newsgroups: pl.comp.lang.java
Subject: Re: Szybkość Javy wg Horstmanna a testy...
Date: Mon, 20 Oct 2008 06:25:11 -0700 (PDT)
Organization: http://groups.google.com
Lines: 66
Message-ID: <24769ac6-ecbd-492d-b655-68805d8fde86@g25g2000prf.googlegroups.com>
References: <gdg318$g5g$1@nemesis.news.neostrada.pl> <df635ef9-4a3f-4915-be18-d2dcf7f09b9f@t18g2000prt.googlegroups.com>
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