用普里姆(Prim)算法构造最小生成树；图的DFS算法的非递归遍历函数-She (Prim) algorithm to construct minimum spanning tree

此程序使用最小生成树Prim算法,用户输入图的输入文件名,程序读此文件(This procedure using minimum spanning tree Prim algorithm, user input figure input file name, program to read this file)