Introduction - If you have any usage issues, please Google them yourself
Need to be in a particular city n laying between gas in residential area, is between the n dweller you just need to lay n- 1 the pipes.Assuming that laying pipes can be between any two communities, but due to the geographical environment is different, need cost are also different.Choose the optimal scheme can make the total investment is as small as possible, the problem is the minimum spanning tree of undirected network.