Special divisors: Difference between revisions
→{{header|Ruby}}: Add Ruby
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Found 72 special divisors N that reverse(D) divides reverse(N) for all divisors D of N, where N < 200
done...
</pre>
=={{header|Ruby}}==
<syntaxhighlight lang="ruby">class Integer
def reverse
to_s.reverse.to_i
end
def divisors
res = []
(1..Integer.sqrt(self)).each do |cand|
div, mod = self.divmod(cand)
res << cand << div if mod == 0
end
res.uniq.sort
end
def special_divisors?
r = self.reverse
divisors.all?{|d| r % d.reverse == 0}
end
end
p (1..200).select(&:special_divisors?)</syntaxhighlight>
{{out}}
<pre>
[1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 13, 17, 19, 22, 23, 26, 27, 29, 31, 33, 37, 39, 41, 43, 44, 46, 47, 53, 55, 59, 61, 62, 66, 67, 69, 71, 73, 77, 79, 82, 83, 86, 88, 89, 93, 97, 99, 101, 103, 107, 109, 113, 121, 127, 131, 137, 139, 143, 149, 151, 157, 163, 167, 169, 173, 179, 181, 187, 191, 193, 197, 199]
</pre>
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