一个连通图可以有多个生成树，实际应用中希望所选的生成树的权值总和最小，这就是最小生成树的问题。代码实现用Kruskal算法实现求解最小生成树。-A connected graph can have multiple spanning tree, hope in the actual application of the selected total weight minimum spanning tree, this is the minimum spanning tree problem. Code implementation with Kruskal algorithm to achieve minimum spanning tree.