修改起泡排序的算法，在正反两个方向交替进行扫描，即第一趟把排序码最大的对象放到序列的最后，第二趟把排序码最小的对象放到序列的最前面。如此反复进行。-Modified bubble sort algorithm, in both directions alternately scanning, sorting code that first trip to the largest objects into the final, the second trip to the smallest object sort code sequence into the front of the sequence. So repeatedly.