需要在某个城市n个居民小区之间铺设煤气管道，则在这n个居民小区之间只需要铺设n-1条管道即可。假设任意两个小区之间都可以铺设管道，但由于地理环境不同，所需要的费用也不尽相同。选择最优的方案能使总投资尽可能小，这个问题即为求无向网的最小生成树。-Needs in a residential area between the n cities laying gas pipelines, in the residential area between the n n-1 only the laying of the pipeline can be. Assumed between any two communities can lay the pipeline, but because of different geographical environment, the required fees are not the same. Choose the best solution to make a total investment of as small as possible, the problem is they try to net a minimum spanning tree.