Introduction - If you have any usage issues, please Google them yourself
The train cars were sent to n n stations stations by 1 ~ n the order number, the train in accordance with n, n-1, ..., 1 after the station number sequence. Suppose car number is the number of their destination station. Given an arbitrary ranking car. Rearrange the car to make it from 1 to n according to the order of arrangement. Rearrangement can only be provided to buffer the tracks from the orbit, or to derail from the track buffer