Test string isomorphism

isomorphism.rb

module CoreExtensions
  module Histogramable
    refine String do
      def to_histogram
        each_char.with_index.each_with_object(Hash.new { |hsh, key| hsh[key] = [] }) { |(ch, index), o| o[ch] << index }
      end
    end
  end
end

class Isomorphism
  using CoreExtensions::Histogramable

  attr_accessor :str1, :str2

  def initialize(str1:, str2:)
    @str1, @str2 = str1, str2
  end

  def isomorphic?
    (@str1.to_histogram.values - @str2.to_histogram.values).count.zero?
  end
end

test1 = Isomorphism.new(str1: 'foo', str2: 'bar')
test2 = Isomorphism.new(str1: 'egg', str2: 'odd')

test1.isomorphic?
test2.isomorphic?