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Discussion of Problem 1533. Fat Hobbits

How to solve correctly?
Posted by Victor Barinov (TNU) 31 Oct 2007 18:20
Hi!

I know that exists theorem:
Minimal number of paths that cover such graph equals to maximal number of independent vertices.

If I found this paths how can i recieve necessary vertices?

Thanks!
Re: How to solve correctly?
Posted by svr 31 Oct 2007 20:21
I think that it is some clever ways to solve NP problems.
It works only in authors limits.
O(n^3)exists!
Apply bipartie maximal cardinality matching.
Standard matchig programm must be
strengthening by finding minimal vertex covering.
All  vertex out of minimal covering - hobbits!


Edited by author 02.11.2007 09:02
Re: How to solve correctly?
Posted by Sandro (USU) 31 Oct 2007 23:21
This problem can be solved in O(N^3) time.
Re: How to solve correctly?
Posted by Denis Koshman 24 Aug 2008 17:34
Victor. To solve what you want, you should find maximum clique in inversed transitive closure graph. Anyway, such level of abstraction leads to NP solution, try some other way. Transitive closure graph has some extra properties which allow O(N^3).