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Discussion of Problem 1520. Empire Strikes Backzhzqkkk To admin [1] // Problem 1520. Empire Strikes Back 16 Apr 2013 11:24 76 85 46 -22 4 15 -10 14 -12 7 -14 20 17 42 11 15 10 -10 60 15 18 -10 43 -51 27 22 -50 -32 -60 -11 -3 -29 -65 -13 -10 2 37 -7 9 -37 -39 42 80 -28 55 -41 -7 -77 -11 17 -6 -54 -55 -48 8 -58 -17 -52 -42 -8 26 -4 24 -13 29 41 -52 14 12 17 55 12 -50 43 27 -8 -33 -78 -42 -2 2 -71 -39 -6 52 -5 -25 62 -51 -2 -19 45 10 12 3 47 -61 37 13 -41 -7 -12 -7 -25 12 15 44 5 -47 -8 -3 -17 -12 -60 -2 28 37 -5 29 -7 -59 61 -17 50 -42 -19 26 51 -10 11 10 5 -1 31 -50 -23 7 -35 29 -47 -5 21 -69 11 13 -17 26 3 13 58 -40 30 -20 -12 please add this test i found many AC program can't pass it.(they use Simulated Annealing) zhzqkkk Re: To admin // Problem 1520. Empire Strikes Back 16 Apr 2013 11:28 58 88 40 -15 16 -18 -35 -53 -26 10 10 -64 -19 33 25 48 75 6 12 -65 29 31 -1 57 30 12 27 17 44 -11 24 -2 16 -25 21 -4 -57 24 51 25 26 20 -12 -27 23 -29 -22 6 13 -4 -11 -57 -18 17 -32 -22 -70 -17 -31 22 -47 69 -53 -64 -23 20 33 10 -13 -8 11 -25 -5 68 73 23 49 -15 68 -31 -33 -56 6 36 -13 -51 0 79 55 36 24 -1 54 -13 -21 -16 16 40 -38 11 15 3 20 -2 18 10 -16 27 -41 23 48 -24 35 -39 -61 10 -51 -14 also a good test at last ,sorry for my poor english Moya WA5...I have no idea about it.Can somebody give me any useful tests? [1] // Problem 1520. Empire Strikes Back 13 Jul 2011 08:46 Moya Re: WA5...I have no idea about it.Can somebody give me any useful tests? // Problem 1520. Empire Strikes Back 13 Jul 2011 09:25 It's my fault... maybe 3 4 1 0 1 0 0 0 is a useful test.The right answer should be 4. cherudim horrible // Problem 1520. Empire Strikes Back 7 Nov 2010 18:48 shangjingbo ignore it.. // Problem 1520. Empire Strikes Back 22 Aug 2009 13:31 ignore it..just my mistake Edited by author 22.08.2009 13:35 shangjingbo WA#12..need help! // Problem 1520. Empire Strikes Back 22 Aug 2009 06:53 Is it a precision problem? who can give me some useful tests? nttjuvwamsncc how to [2] // Problem 1520. Empire Strikes Back 14 Feb 2007 14:35 how to solve it ??? svr Re: how to [1] // Problem 1520. Empire Strikes Back 20 Mar 2008 11:48 I think that enough for each circle-boundary to be covered by others circles or we have covering problem of arc by given set of arcs. Have Ac based on this idea. 1504 ac with the same idea but many hard work with eps. Main difficult moment: ends of arcs computed with help of arcos have error with respect to exact values and may be greater or smaller of them , but exact values of boundaries of intervals lies in distance eps=1.e-16 from computed values. Edited by author 22.03.2008 17:50 Denis Koshman Re: how to // Problem 1520. Empire Strikes Back 30 Aug 2008 05:41 It's Vorony diagrams problem. Of course, you may solve it via covering all arcs of all circles or even try binary search on radius. 2svr: as for comparing arcs - why do you need angles? Just keep x/y pairs defining direction and compare these pairs for <, =, > of angles they define. One of easy easy ways to do that: y>0 || y==0 && x>0 - 1st part [0;pi) y<0 || y==0 && x<0 - 2nd part [pi;2pi) if 2 vectors belong to different parts, you alredy know which angle is smaller. If not, check sign of their cross product. Chmel_Tolstiy WA4. Help. Is there some spesial test ? [-] [2] // Problem 1520. Empire Strikes Back 27 Jun 2007 14:27 Vedernikoff Sergey Re: WA4. Help. Is there some spesial test ? [-] [1] // Problem 1520. Empire Strikes Back 27 Jun 2007 16:38 The only tricky test I see here is N = 1 Chmel_Tolstiy Re: WA4. Help. Is there some spesial test ? [-] // Problem 1520. Empire Strikes Back 27 Jun 2007 17:47 Just a bug :) Hao Hu (Ikki @ Nanjing University) Can you give me a hint on how to solve this? [30] // Problem 1520. Empire Strikes Back 29 Dec 2006 12:17 as the title thanks in advance! EfremovAleksei Re: Can you give me a hint on how to solve this? [28] // Problem 1520. Empire Strikes Back 29 Dec 2006 15:02 Diagram of Voronoy, of course. SPIRiT Re: Can you give me a hint on how to solve this? // Problem 1520. Empire Strikes Back 29 Dec 2006 18:40 Well well, the second problem on Timus that should be solved with diagram of Voronoy SPIRiT Re: Can you give me a hint on how to solve this? [24] // Problem 1520. Empire Strikes Back 29 Dec 2006 18:40 Well well, the second problem on Timus that should be solved with diagram of Voronoy Slam [Tartu U] Re: Can you give me a hint on how to solve this? [23] // Problem 1520. Empire Strikes Back 29 Dec 2006 19:05 What one was first? Sawe Re: Can you give me a hint on how to solve this? [22] // Problem 1520. Empire Strikes Back 29 Dec 2006 19:12 1504 Kit Re: Can you give me a hint on how to solve this? [21] // Problem 1520. Empire Strikes Back 30 Dec 2006 12:42 This problem can be easily solved WITHOUT Voronoi's diagram. I didn't write 1504 yet, but it also doesn't require such complicated methods. EfremovAleksei Re: Can you give me a hint on how to solve this? [5] // Problem 1520. Empire Strikes Back 30 Dec 2006 15:34 I got AC used diagram of voronoi. Kit, please send me your program - efrcom@inbox.ru It's very interesting for me, how solved it without voronoi's diagram. Dmitry 'Diman_YES' Kovalioff Timus-1504 does not require voronoi graph either ;) (-) [4] // Problem 1520. Empire Strikes Back 30 Dec 2006 19:25 SPIRiT Re: Timus-1504 does not require voronoi graph either ;) (-) [3] // Problem 1520. Empire Strikes Back 4 Jan 2007 17:01 I was not talking about 1504. I was talking about 1369 - the Cockroaches problem. Originally it was possible to solve the task with quadtree. But after new tests added to the task quadtree does not work. Therefore a more sophisticated structure is required. SPIRiT Are Saddams coordinates also integer or not [2] // Problem 1520. Empire Strikes Back 4 Jan 2007 18:57 It's not clear. The plants are guaranteed to have integer coordinates. Is that true for Saddam too? If so, it's might be a simple binary search Peter Ivanov Re: Are Saddams coordinates also integer or not // Problem 1520. Empire Strikes Back 5 Jan 2007 20:01 No, it is said that Sassam is somewhere in the circle - not required to be at an integer coordinate. (in fact he is somewhere else but... that's the problem statement - not up to date). -- it would be good to post such question in other topics for the future Dmitry 'Diman_YES' Kovalioff Saddam's coordinates are not necessarily integer (+) // Problem 1520. Empire Strikes Back 5 Jan 2007 20:57 He might be anywhere within the circle. P.S. It is a pity Saddam III has been hang alone. I wonder when George II will follow him ;) 323232 I need an AC solution to this problem [13] // Problem 1520. Empire Strikes Back 11 Jan 2007 15:58 To Kit: I thought it can be solved without Voronoi's diagram, too. But I got Wrong Answer here. Could you send your solution to gaoyihan@gmail.com? I want to check my program. you can only give me the exe-file. Edited by author 11.01.2007 16:24 Dmitry 'Diman_YES' Kovalioff Check your mail. I have sent you an exe-file of my solution (-) // Problem 1520. Empire Strikes Back 11 Jan 2007 16:07 SPIRiT Probability will rule? [11] // Problem 1520. Empire Strikes Back 11 Jan 2007 18:16 I think it's binary search + Monte-Carlo. Is such approach correct? Edited by author 11.01.2007 18:16 Vedernikoff Sergey Re: Probability will rule? [10] // Problem 1520. Empire Strikes Back 16 Jan 2007 15:15 Why Monte-Carlo? I think, you'll get WA, because answer should be very accurate. Use binary search and bruteforce - O(N^3*logN), AC in ~ 0.25 secs. SPIRiT Re: Probability will rule? [8] // Problem 1520. Empire Strikes Back 17 Jan 2007 19:01 I think it's like this. The problem is how to define if for the given radius r the original circle is completely covered? (I don't think that there is a straight formula for 300 points). Therefore I just generate 50 points randomly and for each check does it belong to one of the inner circles or not. If there is a point that does not belong to any of the inner circle, the radius is not big enough, otherwise it's big enough. The binary search is obvious. How do you check the coverage with bruteforce? Any hint or algo? Vedernikoff Sergey Re: Probability will rule? [7] // Problem 1520. Empire Strikes Back 18 Jan 2007 16:46 If you drop only 50 points, you'll not detect many little "white spaces" (when, for example, current radius 1e-3 less, than optimal. Obviously, such a solution will get WA. How to check coverage with bruteforce? Intersect any two circles and consider epsilon neighborhood of their common points... SPIRiT Re: Probability will rule? [2] // Problem 1520. Empire Strikes Back 18 Jan 2007 17:21 Thanks a lot. But perhaps if I increase the number of random points (for each check a separate set of points), I'll get AC (if not from the first time, than from the second thanks to the random :) Vedernikoff Sergey Re: Probability will rule? // Problem 1520. Empire Strikes Back 19 Jan 2007 14:30 To my mind, it's practically impossible. You should check (1000/1e-5)^2 ~ 10^16 points on every step of binsearch to catch "little whitespaces". Quadrotrees can help you a little, but... nttjuvwamsncc Re: Probability will rule? // Problem 1520. Empire Strikes Back 14 Feb 2007 14:35 I don't understand you solution tell me more KIRILL(ArcSTU) Re: Probability will rule? [3] // Problem 1520. Empire Strikes Back 19 Jan 2007 14:46 Vedernikoff Sergey wrote 18 January 2007 16:46 If you drop only 50 points, you'll not detect many little "white spaces" (when, for example, current radius 1e-3 less, than optimal. Obviously, such a solution will get WA. How to check coverage with bruteforce? Intersect any two circles and consider epsilon neighborhood of their common points... Your idea is very good, but how you did it so fast? I have TL16 Vedernikoff Sergey Re: Probability will rule? [2] // Problem 1520. Empire Strikes Back 22 Jan 2007 14:55 Apply some optimixation techniques - precalc, for instance... KIRILL(ArcSTU) Re: Probability will rule? [1] // Problem 1520. Empire Strikes Back 22 Jan 2007 19:13 Vedernikoff Sergey wrote 22 January 2007 14:55 Apply some optimixation techniques - precalc, for instance... Now I have WA17 I do not understand what points should we check If we will check only neighboor points of intersection any 2 circles - it's not right For example 2 1000 1000 0 999 0 Right answer is 1999 But if we will check radius 1000 then both intersection points will lie out of main circle it4.kp Re: Probability will rule? // Problem 1520. Empire Strikes Back 22 Jan 2007 22:25 For each two crossing circles (crossing inside main circle) there must be third one which covers intersection point of the first two circles. nttjuvwamsncc Re: Probability will rule? // Problem 1520. Empire Strikes Back 14 Feb 2007 14:33 can you tell me more about your solution nttjuvwamsncc Re: Can you give me a hint on how to solve this? // Problem 1520. Empire Strikes Back 14 Feb 2007 14:33 how can you solve this problem without the diagram Sawe Re: Can you give me a hint on how to solve this? [1] // Problem 1520. Empire Strikes Back 29 Dec 2006 19:13 Where can I read about diagram of Voronoy? EfremovAleksei Re: Can you give me a hint on how to solve this? // Problem 1520. Empire Strikes Back 29 Dec 2006 23:05 Preparata, Shajmos. Computational geometry. An introdution. Yogesh Re: Can you give me a hint on how to solve this? // Problem 1520. Empire Strikes Back 20 Jan 2007 22:02 theriyaathutaa koothi
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