假定在一舞会上，男士排成一队，女士排成一队。跳舞开始时，依次从男队和女队的队头各出一人配成舞伴。若两队初始人数不相同，则较长的那一队中未配对者等待下一轮舞曲。-Assume that in a ball, lined up a team of men, women lined up a team. Dance begins, followed by men s and women s teams from the teams head out of one pair each partner.