Re: Egyptian fractions (Golf Anyone?)

jimt,
Obfu is not my thing, but I do love interesting math problems. The following is more of a golf (156) than an obfu:

use Math::Pari 'lcm';my($n,$d)=split/\//,shift;sub p{print"1/$_[0] "}w
+hile(1){my
$u=int$d/$n+1;p$u;my $l=lcm$d,$u;$n=$n*$l/$d-$l/$u;$d=$l;p($d),die$/if
+$n==1}
[download]

Golfing with strictures and warnings is a handicap so (146):

($n,$d)=split/\//,shift;sub p{print"1/$_[0] "}while(1){use Math::Pari
lcm;$u=int$d/$n+1;p$u;$l=lcm$d,$u;$n=$n*$l/$d-$l/$u;$d=$l;p($d),die$/i
+f$n==1}
[download]

Since I am not a golfer either, anyone interested in the starting code can use it to improve things.

Cheers - L~R

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Re^2: Egyptian fractions (Golf Anyone?) by liverpole (Monsignor) on Aug 25, 2006 at 15:37 UTC
Hi Limbic~Region, A couple of small changes will get you down to 142: `($n,$d)=split'/',shift;sub p{print"1/$_[0] "}{use Math::Pari lcm;$u=int$d/$n+1;p$u;$l=lcm$d,$u;$n=$n*$l/$d-$l/$u;$d=$l;p($d),die$/i +f$n==1;redo}` [download] s''(q.S:$/9=(T1';s;(..)(..);$..=substr+crypt($1,$2),2,3;eg;print$..$/	[reply] [d/l]
Re^3: Egyptian fractions (Golf Anyone?) by tadman (Prior) on Aug 25, 2006 at 17:13 UTC
Refinement of this particular track at 130: `($n,$d)=split'/',pop;sub p{print"1/@_ "}{use Math::Pari lcm;p$u=int$d/$n+1;$l=lcm$d,$u;$n=$n*$l/$d-($d=$l)/$u;$n-1?redo: p$d+die$/}` [download]	[reply] [d/l]
Re^2: Egyptian fractions (Golf Anyone?) by blokhead (Monsignor) on Aug 25, 2006 at 16:43 UTC
81 chars: `$ perl -e '($n,$d)=split"/",pop;{1while++$x<$d/$n;warn"1/$x\n";$n=$n$ +x-$d;$d=$x;redo if$n}' 18/20 1/2 1/3 1/15` [download] Update: changing the entire structure to a C-style `for`-loop saves 2 chars, so this gives me a 79-char solution: `for(($n,$d)=split"/",pop;$n;){1while++$x<$d/$n;warn"1/$x\n";$n=$n$x-$ +d;$d=$x}` [download] <Reveal this spoiler or all in this thread> blokhead	[reply] [d/l] [select]
Re^2: Egyptian fractions (Golf Anyone?) by shmem (Chancellor) on Aug 26, 2006 at 01:53 UTC
Ah, no, Limbic~Region, your's ain't golf. No modules, lest I would say `use Junk;do` [download] - 11 chars.. but that could be golfed down to `use J;d` - 7 chars ;-) blokhead's solutions look neat, but they hog my cpu... (with 2355/12344 - still not finished in 3/4 hour ;-) #!/usr/bin/perl -l pop=~m\|/\|;($f,$g)=($`,$');sub d{int($_[1]/$_[0]+1)}sub g{($x,$y)=@_;($x,$y)=($y,$x% $y)while$y;$x} sub re{($p ,$e,$r,$l)=@_;($p,$l)=($p$l-$e$r,$e$l);$g=g($p,$l); for($p,$l){$_/=$g};($p,$l)}while($f>1){push@o,"1/".d(# $f,$g);($f,$g)=re($f,$g,1,d($f,$g));}print join' + ',# @o,"$f/$g";# ungolfed and thus not for production use! [download] way too long... <update> golfed down a bit... (198 chars, counting newlines). `($z,$n)=($_=pop)=~/(.+)\/(.+)/;$s='==';for(;;){$m=int($n/$z+1);$_ .=" $s 1/".($z==1?$n:$m);$z<=1&&last;($z,$n)=($z$m-$n,$m*$n);($x ,$y)=($z,$n);($x,$y)=($y,$x%$y)while$y;$z/=$x;$n/=$x;$s='+'}print` [download] It computes egyptian fractions like this `qwurx [shmem] ~> perl -l egy.pl 2355/12344 2355/12344 == 1/6 + 1/42 + 1/3282 + 1/15755059 + 1/744665636525384` [download] in no time... </update> --shmem _($_=" "x(1<<5)."?\n".q·/)Oo. G°\ / /\_¯/(q / ---------------------------- \__(m.====·.(_("always off the crowd"))."· ");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}	[reply] [d/l] [select]
Re^3: Egyptian fractions (Golf Anyone?) by dewey (Pilgrim) on Aug 26, 2006 at 03:04 UTC
A modification of blokhead's idea... what golf can go without regular expressions? 72 strokes: for($_=pop;/\//,$`;$_=$x$`-$'.'/'.$'$x){1while++$x<$'/$`;print"1/$x "} [download] I counted the line break as one character, is that kosher? Update: I see also shmem had a similar thought, I had missed that before posting somehow. Update again: Changed the title of this node to not be dumb. Sorry all, thanks for the feedback those who messaged me! ~dewey	[reply] [d/l]