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## Discussion of Problem 1429. Biscuits

any hints for this problem~~ ?
Posted by I hope nobody will be hurt. 25 Jun 2006 07:56
thanks~~
Re: any hints for this problem~~ ?
Posted by N.M.Hieu ( DHSP ) 25 Jun 2006 14:35
[text deleted]

From the moderator: It is inadvisable to explain solutions of difficult problems. I have the right to delete such explanations.

Edited by moderator 25.06.2006 23:01
Re: any hints for this problem~~ ?
Posted by Denis Koshman 29 Aug 2008 04:12
I'll post my hint because it is a general approach and common theory rather than a solution for this particular problem.

For 3D primitives there is Euler formula v+f-e=2 where 'v' is number of vertices, 'f' is number of faces and 'e' is number of edges (plus/minus is easy to memorize via parallelepiped, v=8, f=6, e=12, so only v+f-e=2 gives the right answer).

This formula also applies to planar graphs in the form v+f-e-c=1 where 'c' is number of connected components, and outer face of planar graph is also counted.