中文说明：用于计算两点之间的最短路径，从A点到D点有很多路径，但是每一条路经过的站点不同，所以所占的权重不同，给定一张路径图，输入起点，终点，最后得到最短路径显示。
English Description：
It is used to calculate the shortest path between two points. There are many paths from point a to point D, but each path passes through different stations, so the weight is different. Given a path map, enter the starting point and end point, and finally get the shortest path display.