From: James Coglan <jcoglan@...>
Date: 2008-09-21T18:54:10+09:00
Subject: Re: One-Liners Mashup (#177 again)

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2008/9/21 Sebastian Hungerecker <sepp2k@googlemail.com>

> James Coglan wrote:
> > def per(n, p = 16)
> >   (1..(p/2)).detect { |x| ("%.#{p}f" %
> > (1.0/n)).split(".").last.scan(%r{.{#{x}}}).uniq.size == 1 } || 0
> > end
> >
> > This produces correct output for the numbers you specified.
>
> It produces 0 for 6 though (because printf rounds instead of truncating so
> you
> get a 7 at the end).
> Here's one that should always be accurate and it's even in 1 line and
> handles
> different bases:
> def per(n, b = 10)
>  i=1;x=b;h={};loop {x=x%n*b;break 0 if x==0;h[x]?(break i-h[x]):h[x]=i;
> i+=1}
> end


Would be interested to see if you could produce a version with no
assignments or semicolons. With Ruby's functional and OO capabilities, it's
always more satisfying if you can solve a problem with a single statement,
and I think these little one-liner problems are great for getting you
thinking in functional style.

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