From: Sebastian Hungerecker <sepp2k@...>
Date: 2009-01-19T18:59:28+09:00
Subject: Re: reading file to list

André Thieme wrote:
> Now that I was so kind to give you what you asked for, you will
> probably do the same for me and show me your Ruby code, in which you
> define a variable that contains the Fibonacci sequence.
>
> (def fibs (lazy-cat [0 1] (map + fibs (drop 1 fibs))))
>
>
> (nth fibs 70) ==> 190392490709135
>
> One requirement is that when you look at the n'th fib the results up
> to n must be memoized, so that nothing needs to be calculated again
> when you ask for a fib between 0 and n. And when you ask for the n+1'th
> it will start the calculation right from point n.

fibs = Hash.new {|h,k| h[k] = h[k-1] + h[k-2]}.merge(0=>0, 1=>1)
fibs[70] #=> 190392490709135

HTH,
Sebastian
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