055 Lychrel numbers.sf

#!/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
    }
})