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There is some trash in the end of file. There is theory of Ramsei. if you want 4 you need 5 points. if you want 5 you need 9 points. Edited by author 03.02.2009 14:53 Thanks for 9 and for Ramsei. Owing to your post I've read something of theory of Ramsei. And I find it enough curious. Thanks for it. Thanks a lot. Very interesting theory. So, if the pigeon is black or white, how does this work? Edited by author 06.01.2011 15:52 But what proove? Edited by author 28.12.2008 23:42 According to the time limit and N size we cannot use O(N^3). Therefore it should be O(N^2) or O(N^2*lnN). What's the trick? O(N^2) - it's just to select two points. How to find other three quickly? Perhaps they should be chosen randomly? Or maybe we should use Graham scan as many times as possible, to see what we get? Is there really such an algo? You don't have to tell me the idea, just say that there is such an algo... Theoretically, O(C(5,N)), but in a practice - O(1) :) I thought about this problem. It can be proven, that you can build a polygon with 4 vertices from any 5 that don't lie on the same line (that is one of the statements). How many vertices does one need to build a 5 vertex convex polygon (I think about 10 or 15)... There exists an algorithm with O(N*h) complexity... I WA on Test22 for many times...I don't why... Anyone can tell me what special things in the Test22,or give me the data to my Email:zej88889@163.com Thanks. [hint deleted] Edited by moderator 16.05.2007 09:25 |
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