This program use for topological sorting

数据结构中的拓扑排序，用拓扑排序来完成大学四年的课表排序，从文本文档中读取课程（乱序）课时，序号等信息，根据先修后修的原定顺序，按照拓扑排序来完成课表。-topo assessment in structure of computer,to finish the timetable for the whole four years at colleage. Read information from a text,an the number of the subjects and the m