From: Robert Klemme <shortcutter@...>
Date: 2008-05-03T17:40:16+09:00
Subject: Re: [QUIZ] Reverse Divisible Numbers (#161)

On 02.05.2008 18:44, Rob Biedenharn wrote:
> On May 2, 2008, at 12:10 PM, Ken Bloom wrote:
> 
>> On Fri, 02 May 2008 10:28:00 -0500, Matthew Moss wrote:

>> Here's what I've found:
>>
>> 1089 * 9 = 9801
>> 2178 * 4 = 8712
>> 10989 * 9 = 98901
>> 21978 * 4 = 87912
>> 109989 * 9 = 989901
>> 219978 * 4 = 879912
>>
>> real	0m55.234s
>> user	0m53.995s
>> sys	0m0.012s
>>
>> --Ken
>>
>> -- 
>> Ken (Chanoch) Bloom. PhD candidate. Linguistic Cognition Laboratory.
>> Department of Computer Science. Illinois Institute of Technology.
>> http://www.iit.edu/~kbloom1/
> 
> 2178 * 4 = 8712
> 1089 * 9 = 9801
> 21978 * 4 = 87912
> 10989 * 9 = 98901
> 219978 * 4 = 879912
> 109989 * 9 = 989901
> 
> real	0m13.113s
> user	0m12.411s
> sys	0m0.081s
> 
> While I find them in a slightly different order, I'm surprised by the  
> 4x speedup.  I wonder if there's a better way to post comparisons that  
> would negate machine differences and focus on algorithmic distinctions  
> without posting code?

My pretty straightforward solution:

robert@fussel /cygdrive/c/Temp
$ time ./quiz-161.rb 1_000

real    0m0.591s
user    0m0.045s
sys     0m0.170s

robert@fussel /cygdrive/c/Temp
$ time ./quiz-161.rb 1_000_000
8712
9801
87912
98901
879912
989901

real    0m3.981s
user    0m3.764s
sys     0m0.108s

robert@fussel /cygdrive/c/Temp
$ time ./quiz-161.rb 10_000_000
8712
9801
87912
98901
879912
989901
8799912
9899901

real    0m38.022s
user    0m37.530s
sys     0m0.155s

robert@fussel /cygdrive/c/Temp
$ time ./quiz-161.rb 100_000_000
8712
9801
87912
98901
879912
989901
8799912
9899901
87128712
87999912
98019801
98999901

real    6m21.099s
user    6m19.639s
sys     0m0.108s

robert@fussel /cygdrive/c/Temp
$ wc quiz-161.rb
   8  36 173 quiz-161.rb

robert@fussel /cygdrive/c/Temp
$

Cheers

	robert