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in reply to Re: (Golf) Kaprekar's Process
in thread (Golf) Kaprekar's Process

... it handles 0s in numbers correctly 
a(100)

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There are many such cases, though I misstated the problem somewhat. It isn't so much zeroed digits, as intermediate two-digit results. So far, all the solutions in this thread (except my own :) fail on many three-digit numbers.

Also, in Golf, it may be ok to violate strict, but your subroutine should be re-runnable (ie. $i should be reset somewhere). 

   MeowChow                                   
               s aamecha.s a..a\u$&owag.print

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Re: Re: Re: (Golf) Kaprekar's Process
by srawls (Friar) on Jun 16, 2001 at 23:41 UTC
    Oh, I see: 100 - 001 is 99; 99 - 99 is zero. Now we've got an infinite loop. Just out of curiosity, how would you solve that? Your solution gives 6 (which is most likely right), I just don't see how.

    The 15 year old, freshman programmer,
    Stephen Rawls

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      That's what the sprintf is there for. It formats a two-digit result into a three-digit string, eg. 099. After sorting and reversal, you get 990 - 099. 
         MeowChow                                   
               s aamecha.s a..a\u$&owag.print
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        Ok, I get it. I can modify yours than, and improve it by two chars: 
        sub a {
$_=pop;s/^..$/0$&/;/495/?0:1+a(-($_=join'',sort/./g)+reverse)
}

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        The 15 year old, freshman programmer,
        Stephen Rawls

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[d/l]

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