该程序用贪心算法来求解最小生成树问题 采用贪婪准则：每次选择边权值最小边。如果该边加入后不构成环，则加入。-procedures with the greedy algorithm to solve the problem using the minimum spanning tree greedy guidelines : each side the right to choose the minimum value side. If the edge after the entry does not constitute a part, while accession.