输入学期总数 学期的学分上限 课程数 拓扑排序所形成的课程先修关系的边数 课程号及其学分 在各学期学期负担尽量均匀和 课程集中在前几个学期进行排课两种条件下进行排课-importation of the total semester credit semester courses ceiling few topological sorting as a result of the pre-course edge courses, and credits in the semester to