It took me a fair bit of refactoring after I got the last test passing (generate 10 ) to get it this tight, but I like it.
def generate(n)
return [] if n == 1
factor = (2..n).find {|x| n % x == 0}
[factor] + generate(n / factor)
end
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November 13, 2009
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» Kata:Ruby:Tail Recursive Prime Factors from Radyology
At the request of a former employer here's a tail recursive version of the prime factors kata in Ruby. def generate(n, factors=[]) return factors if n == 1 new_factor = (2..n).find {|f| n % f == 0} generate(n / new_factor,... [Read More]
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Nice. Stuff like this makes me continue believe in programming.
Posted by: Fredrik Rubensson | November 27, 2009 at 08:48 AM
Can you make this tail recursive
Posted by: unclebob | December 05, 2009 at 09:48 AM
Sure can:
http://www.benrady.com/2009/12/katarubytail-recursive-prime-factors.html
Posted by: Ben Rady | December 05, 2009 at 02:50 PM
This is really amazing. After staring this code for few minutes, I realized that the trick here is the fact that any number can be expressed as factors of only prime numbers and nothing else.
Posted by: Srikanth P Shreenivas | October 04, 2010 at 04:15 AM