（1）采用邻接表作为有向图的存储结构； （2）给出所有可能的拓扑序列。 （3）测试用例见严蔚敏《数据结构习题集(C语言版)》p48题7.9图 -(1) adjacency list used as the storage structure of directed graphs (2) gives the sequence of all possible topologies. (3) test cases, see Ya

严蔚敏版本的数据结构课后习题，考研，复习必备(Yan Yumin version of the data structure after-school exercises, PubMed, review essential)