火车车厢重排问题:给定一个任意的车厢排列次序。重新排列车厢，使其按照从1到n的次序排列。规定重排时只能从入轨到缓冲铁轨，或者从缓冲铁轨到出轨。-Train cars rearrangement problem: given an arbitrary compartment order of merit. Rearrange the cars, so that from 1 to n according to the order. Rearrangement can only be provided to the buffer from the orbit track, or tracks from the buffer to the derailment.