开发一个公交线路查询程序，可以查询出从A站到B站的直达路线和换乘路线，并支持指定必须经过C站的从A站到B站的公交路线查询。这个问题暗含的前提是要实现公交路线图的建立，显示和修改功能，为查询提供存储结构依据和数据支持。-Develop a bus line query procedures, you can check out the direct route from station A to station B and transfer routes, and support the designated bus route from station A to station B C station must go through query. The implicit premise of this question is to realize the establishment of bus routes map, display and modify the function to provide storage for the query structure basis and data support.