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Henrik Torstensson
Tue 7-Jun-2011 22:56 | *Spoiler alert*
Here is my solution: http://pastebin.com/DpNHxAA8 | Anonymous
Wed 13-Jul-2011 17:29 | 1.This is my answer to Linus Åkesson's Java challenge <http://www.linusakesson.net/programming/what/java1.php>.
2.
3.The Java program multiplies two numbers given as arguments. Example:
4.
5. laban@femto:~/tmp$ java Main 238 13
6. 3094
7.
8.The multiplication is done using "Ancient Egyptian multiplication", see <http://en.wikipedia.org/wiki/Ancient_Egyptian_multiplication>.
9.
10.The recurse() function is always called 30 times. The last time it will raise a java.lang.ArithmeticException because a division by zero occurs when n = 0.
11.
12.The exception from the example above looks as follows:
13. java.lang.ArithmeticException: / by zero
14. at Main.recurse(Main.java:5)
15. at Main.recurse(Main.java:7)
16. at Main.recurse(Main.java:5)
17. at Main.recurse(Main.java:5)
18. at Main.recurse(Main.java:7)
19. at Main.recurse(Main.java:7)
20. at Main.recurse(Main.java:7)
21. at Main.recurse(Main.java:7)
22. at Main.recurse(Main.java:7)
23. at Main.recurse(Main.java:7)
24. at Main.recurse(Main.java:7)
25. at Main.recurse(Main.java:7)
26. at Main.recurse(Main.java:7)
27. at Main.recurse(Main.java:7)
28. at Main.recurse(Main.java:7)
29. at Main.recurse(Main.java:7)
30. at Main.recurse(Main.java:7)
31. at Main.recurse(Main.java:7)
32. at Main.recurse(Main.java:7)
33. at Main.recurse(Main.java:7)
34. at Main.recurse(Main.java:7)
35. at Main.recurse(Main.java:7)
36. at Main.recurse(Main.java:7)
37. at Main.recurse(Main.java:7)
38. at Main.recurse(Main.java:7)
39. at Main.recurse(Main.java:7)
40. at Main.recurse(Main.java:7)
41. at Main.recurse(Main.java:7)
42. at Main.recurse(Main.java:7)
43. at Main.recurse(Main.java:7)
44. at Main.recurse(Main.java:7)
45. at Main.main(Main.java:12)
46.
47.Note the line numbers in the stack trace. The line number is 5 or 7 depending on if the 31st least significant bit in x is set or not. If you add debug code in the recurse() function, the line numbers might change and the program will stop working. :)
48.
49.The catch block in the code will perform the multiplication according to the "Ancient Egyptian" algorithm. | Oscar2
Wed 25-Jan-2012 02:58 | It does the same thing on both sides of the if:
if(0 != (x & 1073741824))
recurse(x * 2, n - n / n);
else
recurse(x * 2, n - n / n);
Did you mean to do that?
I don't see this thing doing the Egyptian multiplication described in the previous post. |
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