> As I anticipate being unable to decipher any of the winning solutions,
> I'd be much obliged if some of you better-than-median folks would post
> an ungolfed Alternate solution illustrating your approach.
Ungolfing is a bit hard, I guess. But some time ago, someone on this
list proposed that every time someone explained his/her solution, so
here it goes.
#!/usr/bin/perl -pl
@;=grep{$'./[6-9]/eq(($x=$`)^$_)=~y/ //.$".grep$x=~s/$_//,/./g}/ /%1x4..5x4,@;}{$_=pop@
The basic idea is to make a list of all candidate solutions, and for each
input line to filter out only those candidate solutions that satisfy
that input line.
The list of candidate solutions is stored in array @;. For each input
line, a full list of new candidates is generated, and together with the
list in @;, fed into the big grep{...} expression. Thus, the last
element(s) in @; have satisfied all input lines, and after all input is
processed,
$_=pop@
gives the only viable solution.
The expression / /%1x4..5x4 generates all 4-digit (0-5) strings, plus
some strings containing digits 6-9, so those must be weeded out yet.
As a "side-effect", the expression splits the input line in two:
$` containing the 4-digit string, and $' containing the number of black
pegs, a space, plus the total number of pegs.
Within the grep, these peg numbers are calculated for the candidate
solution:
a) (($x=$`)^$_) xors character-wise the candidate solution with the
input line; if a digit is on the right spot, this xor yields a
NUL character, which are counted by the y///.
b) grep$x=~s/$_//,/./g counts the total number of pegs. For each digit
in the candidate, the s/// looks if it occurs in the input line
string ($x, which is a copy of $`) and removes it, so digits are not
counted doubly.
These two numbers are string-concatenated with a space ($") in between,
and the resulting string string-compared with the results from the input
line ($').
Finally, to weed out those candidates containing digits 6-9, $' is
concatenated with /[6-9]/: the latter expression yields the empty string
if no such digits occur, else string "1".
Hope this helps!
Cheers,
Daniel
--
Daniël Tuijnman
[EMAIL PROTECTED]
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