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单点时限: 2.0 sec
内存限制: 256 MB
Farmer John had just acquired several new farms! He wants to connect the farms with roads so that he can travel from any farm to any other farm via a sequence of roads; roads already connect some of the farms.
Each of the () farms (conveniently numbered ..) is represented by a position on the plane (, ). Given the preexisting roads () as pairs of connected farms, help Farmer John determine the smallest length of additional roads he must build to connect all his farms.
4 1 1 1 3 1 2 3 4 3 1 4
Four farms at locations (1,1), (3,1), (2,3), and (4,3). Farms 1 and 4 are connected by a road.
Connect farms 1 and 2 with a road that is 2.00 units long, then connect farms 3 and 4 with a road that is 2.00 units long. This is the best we can do, and gives us a total of 4.00 unit lengths.