说明：  Many interesting route planning problems can be solved by computing shortest paths in a suitably modeled, weighted graph representing a transportation network. Such networks are naturally road networks or timetable networks of public transportation. For large networks, the classical Dijkstra algorithm to compute shortest paths is too slow. And therefore have faster algorithms been developed in recent years. These new algorithms have in common that they use precomputation and store auxiliary data to speedup subsequent shortest-path queries.