require "topchart/version"

class Topchart
  def chart(list1,list2)
    chart = []

    rlist1 = list1.reverse
    rlist2 = list2.reverse

    s1 = Set.new(list1)
    s2 = Set.new(list2)

    new = s2 - s1

    chart += new.map do |el|
      [rlist2.index(el), el]
    end

    inter = s1.intersection(s2)
    chart += inter.map do |el|
      i1 = list1.index(el)
      i2 = list2.index(el)
      [i1-i2, el]
    end

    chart.sort.reverse
  end
end