栈混洗的再现。原来的目的是为了求解：一队列车编号为1、2、3、……顺次进入一个站，再按照“后进先出”的原则退出该站点继续前行，问火车后来的给出的行进顺序是否可能。-Stack shuffle reproduction. The original purpose of solving: a team of train numbered 1,2,3, ... ... turn into a station, and then in accordance with the " Last In