class Array
  def shuzzle
    providers = Provider.find(:all).map {|it| it.id}
    set = []
    providers.each do |p|
      grp = []
      self.each {|it| grp << it if it.provider_id == p}
      set << grp
    end
    result = []
    set.each {|it| result.push(it.pop) if it.any?} while set.flatten.any?
    return result
  end
end

Products.find(:all).shuzzle