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  1. /* package whatever; // don't place package name! */
  2.  
  3. /* Testowanie przy ilu liczbach warto tworzyć sito Eratostenesa
  4.  */
  5. public class Main
  6. {
  7.     public static void main(String[] args)
  8.     {   
  9.         int n = 2000000;
  10.         if(args.length>0)
  11.         {
  12.             try
  13.             {
  14.                 n = Integer.parseInt(args[0]);             
  15.             }
  16.             catch(Exception e)
  17.             {
  18.             }
  19.         }
  20.         boolean[] notPrimes = new boolean[n+1];
  21.         long start = System.nanoTime();
  22.         for(int i=2;i*i<=n;i++)
  23.         {
  24.             if (notPrimes[i])
  25.                 continue;
  26.             for (int j=2*i;j<=n;j+=i)
  27.                 notPrimes[j] = true;
  28.         }
  29.         long time = System.nanoTime()-start;
  30.         System.out.printf("Tworzenie sita (w ms): %10.3f \n",time/1000000.0);
  31.         start = System.nanoTime();
  32.         long sum = 0;
  33.         for(int i=2;i<n;i++)
  34.         {
  35.             if(!notPrimes[i])
  36.             {
  37.                 sum+=i;
  38.             }
  39.         }        
  40.         time = System.nanoTime()-start;
  41.         System.out.printf("Czas sumowania (w ms): %10.3f \n",time/1000000.0);
  42.         System.out.println(sum);
  43.     }
  44. }
Success #stdin #stdout 0.1s 381312KB
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stdin
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Standard input is empty
stdout
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Tworzenie sita (w ms):     19.345 
Czas sumowania (w ms):      9.167 
142913828922
https://ideone.com/DECJ9C
language:
Java (HotSpot 12)
created:
10 years ago
visibility:
public

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