euler/ruby/euler004.rb

require_relative 'euler'

def products_of_three_digits
  [].tap do |products|
    (100..999).each do |i|
      (100..999).each do |j|
        products << i*j
      end
    end
  end
end

def solution
  products_of_three_digits.select { |x| Euler.palindrome?(x) }.max
end