Scheduler - cleaned up version of Evgeny Kluev's solution http://stackoverflow.com/a/11761192/6962

scheduler.rb

class Scheduler
  def initialize
    @schedule = []
    @word = 0
  end

  def next_slot
    if @schedule.empty?
      slot = 0
    else
      bit = 32
      while  (((@word ^= bit) & bit) == 0) do
        bit >>= 1;
      end
      slot = (@word * 60) / 64
    end

    @schedule << slot
    @schedule.sort!
    slot
  end

  def schedule
    @schedule
  end
end


scheduler = Scheduler.new

60.times do
  scheduler.next_slot
  p scheduler.schedule
end