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### Re: (Golf) Kaprekar's Process

by srawls (Friar)
 on Jun 16, 2001 at 23:19 UTC ( #89085=note: print w/replies, xml ) Need Help??

in reply to (Golf) Kaprekar's Process

I've taken all the advice and improved my old one to this, 61 char solution (I counted manually this time : ). Oh, and it handles 0s in numbers correctly (well, I don't know if it's correct, but it doesn't freeze up like before). Here it is:
```sub a {
\$_=pop;/495/&&\$i||do{\$_=join'',sort/./g;\$i++;a(reverse()-\$_)}
#234567890123456789012345678901234567890123456789012345678901
}

Update:Changed code from 65 chars to 61.

The 15 year old, freshman programmer,
Stephen Rawls

Replies are listed 'Best First'.
Re: Re: (Golf) Kaprekar's Process
by MeowChow (Vicar) on Jun 16, 2001 at 23:33 UTC
... it handles 0s in numbers correctly
```a(100)
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```
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

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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