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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class Ideone
  9. {
  10. 	public static void main (String[] args) throws java.lang.Exception
  11. 	{
  12.         System.out.println((-10) >>> 1);
  13.         System.out.println((-10) >> 1);
  14.         System.out.println((-11) >> 1);
  15.         System.out.println((-11) / 2);
  16.         for (int x = -10; x < 10; ++x)
  17.         {
  18.             if (((x - (x >> 31)) >> 1) != x / 2) System.out.println("Not equal for: " + x);
  19.         }
  20.  
  21.         int bounds = 80000000;
  22.         long start = System.nanoTime();
  23.         for (int i = -bounds; i < bounds; ++i)
  24.         {
  25.             int r = ((i - (i >> 31)) >> 1);
  26.         }
  27.         long run1 = System.nanoTime() - start;
  28.         start = System.nanoTime();
  29.         for (int i = -bounds; i < bounds; ++i)
  30.         {
  31.             int r = i / 2;
  32.         }
  33.         long run2 = System.nanoTime() - start;
  34.  
  35.         System.out.printf("Run 1: %10d\n", run1);
  36.         System.out.printf("Run 2: %10d\n", run2);
  37. 	}
  38. }
Success #stdin #stdout 4.16s 320576KB
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stdin
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Standard input is empty
stdout
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2147483643
-5
-6
-5
Run 1:  295044177
Run 2: 3749731100
https://ideone.com/aKDShA
Division by pow of two optimization
language:
Java (HotSpot 12)
created:
8 years ago
visibility:
secret

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