Dijkstra算法思想：每次从V-S取出具有最短特殊路径长度的顶点u，将u添加到S中同时对数组dist作必要的修改，一旦s包含了所有v中顶点，dist就记录了从源到其他顶点之间的最短路径长度。-Dijkstra Algorithm idea: Every time out from the VS special path with the shortest length of vertex u, u will be added to the S in the same time, make t