euler/euler005.rb

require_relative 'euler'
require 'prime'

def factorization_of_integer_divisible_by_all_integers_up_to(n)
  {}.tap do |factorization|
    (2..n).map do |i|
      Prime.prime_division(i).map do |factor|
        factorization[factor.first] = factor.last if (!factorization.include?(factor.first) || (factor.last > factorization[factor.first]))
      end
    end
  end
end

def factors_to_int(factorization)
  [].tap do |result|
    factorization.each do |prime, exponent|
      result << prime ** exponent
    end
  end.inject(:*)
end

def solution
  factors_to_int(factorization_of_integer_divisible_by_all_integers_up_to(20))
end