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- #!/usr/bin/ruby
- # Author: Trizen
- # Date: 16 August 2016
- # Edit: 15 March 2023
- # https://github.com/trizen
- # https://projecteuler.net/problem=55
- # Runtime: 0.938s (previously: 1.316s)
- say (^10_000 -> count_by { |n|
- ^49 -> none {
- n += n.flip
- n.is_palindrome
- }
- })
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