实现Dijkstra算法：算法首先打印一个图，然后用户给出一个起始点和终止点，算法就可以给出这两个点之间的最短距离，或提示没有路径。-Implementation Dijkstra algorithm: algorithm first print a map, then give users a starting point and termination point, the algorithm can give these two points the shortest distance between, or prompts no path.