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Discussion of Problem 1710. Boris, You Are Wrong!andreyDagger If you don't understand first sample // Problem 1710. Boris, You Are Wrong! 21 Feb 2022 17:06 Pay attention, that points given in order A, B, C. That means that angle of your triangle must equal to angle BAC Edited by author 21.02.2022 17:07 Tuz 1710 always WA at 26 [2] // Problem 1710. Boris, You Are Wrong! 9 Sep 2009 14:06 I have got WA at 26 several times. Is there something should i pay attention to ? Thank you. Anatoly Re: 1710 always WA at 26 [1] // Problem 1710. Boris, You Are Wrong! 15 Sep 2009 22:07 I had WA 26 when I used "cout << x...", but I've replaced it with "cout << setprecision(15) << x..." and it works. Edited by author 15.09.2009 23:17 alp Re: 1710 always WA at 26 // Problem 1710. Boris, You Are Wrong! 3 May 2014 22:57 if you check angle=pi/2, don't use scalar product. and setprecision(10) Mes Why this is not correct? // Problem 1710. Boris, You Are Wrong! 24 Apr 2014 14:04 I keep getting wrong answer at the 2 example. Isn't it from the examples provided? If so, why for 0 0 4 3 6 0 the solution NO 0 0 5 0 1.6 1.2 is not correct? A1B1 is equal to A2B2, B1C1 is equal to B2C2, C1A1 is different from C2A2, the cosine is the same, therefore the angle is the same. wRabbits_AlMag(VNTU) Tests [2] // Problem 1710. Boris, You Are Wrong! 27 Jul 2011 16:30 For wa#3: 4 0 0 3 0 0 YES For wa#4 0 0 5 0 6 5 YES Fcdkbear[VNTU] Re: Tests [1] // Problem 1710. Boris, You Are Wrong! 27 Jul 2011 21:32 For wa#5 0 0 4 0 2 3 The possible answer is: NO 0.00000000000000000000 0.00000000000000000000 4.00000000000000000000 0.00000000000000000000 0.46153846153846145000 0.69230769230769285000 But i still have have wa#31. I think, I have problem with precision. Can anyone tell me how to avoid this problem? UPD: Finaly AC. I think, it realy was a problem with precision, but I am not sure. Edited by author 27.07.2011 22:20 Edited by author 27.07.2011 23:58 ValentinPerm Re: Tests // Problem 1710. Boris, You Are Wrong! 19 Mar 2014 16:25 Yes, problem in precision. EPS = 1e-10 AC EPS = 1e-11 WA#36 George Agapov Can't understand first sample // Problem 1710. Boris, You Are Wrong! 13 Jan 2012 21:53 Look, using the theorem we could build a triangle with such vertexes: NO -1.0000000000 4.0000000000 0.0000000000 0.0000000000 -0.8780487805 3.9024390244 (img: http://ge.tt/9klV3HC/v/0 ) Iliya Why???? [2] // Problem 1710. Boris, You Are Wrong! 26 Feb 2010 12:59 Could you help me. Why the answer in first test is YES. why not -2 0 -1 4 4 0 Iliya Re: Why???? [1] // Problem 1710. Boris, You Are Wrong! 26 Feb 2010 13:01 Sorry. I have found my mistake. TereshinVS Liceum#165 Re: Why???? // Problem 1710. Boris, You Are Wrong! 18 Mar 2010 21:49 Please tell me why it can't be. I have the same answer on this test Vedernikoff Sergey (HSE: АОП) Useful tests for you, guys [5] // Problem 1710. Boris, You Are Wrong! 12 Apr 2009 15:01 0 0 0 1000 1 0 YES 0 0 1 1000 1 0 YES 0 0 1 1000 2 0 YES Smilodon_am Re: Useful tests for you, guys [1] // Problem 1710. Boris, You Are Wrong! 18 Apr 2009 17:57 Real thanks, Sergey. I had WA3. When I test my program with your tests, I get wrong answer on the second test. My mistake was in comparing the angle ACB with 90 degrees. There was (in C++): if (angle==pi/2.0)... but the right text would be: if (fabs(angle-pi/2.0)<=1e-11)... When I fixed the problem I got AC. Vedernikoff Sergey (HSE: АОП) Re: Useful tests for you, guys // Problem 1710. Boris, You Are Wrong! 21 Apr 2009 16:52 Never forget to use EPS when compare real numbers. Without it, result of the work of your program is almost unpredictable Oleg Strekalovsky [Vologda SPU] Re: Useful tests for you, guys [1] // Problem 1710. Boris, You Are Wrong! 18 May 2009 00:12 Vedernikoff Sergey (HSE: АОП) wrote 12 April 2009 15:01 0 0 0<=|x|,|y|<=1000 1000 1 0 YES 0 0 1 1000 1 0 YES 0 0 1 1000 2 0 YES But tests are useful :) Edited by author 18.05.2009 12:28 Vedernikoff Sergey (HSE: АОП) Re: Useful tests for you, guys // Problem 1710. Boris, You Are Wrong! 19 May 2009 21:05 If 1000 insted of 100 prevents your program from passing the tests, then your program is really horrible =) P.S. I've written 1000 instead of 100 as a very corner cases specially to test possible error instability. Sevenk Re: Useful tests for you, guys // Problem 1710. Boris, You Are Wrong! 29 Aug 2009 09:54 I have known that. Leonid (SLenik) Andrievskiy Подсказка к решению или Как показать, что теорема неверна. [1] // Problem 1710. Boris, You Are Wrong! 20 Jun 2009 16:47 Попытался разобраться как строить треугольник A2B2C2 и случайно додумался вот до такого "доказательства" теоремы Бориса: 0. Дано: A1B1 = A2B2, B1C1 = B2C2, ∠ B1A1C1 = ∠ B2A2C2. 1. По теореме синусов из перечисленного в п. 0 находим, что sin(∠ B2С2A2) = (A2B2 * sin(∠ B2A2C2)) / B2C2 и sin(∠ B1С1A1) = (A1B1 * sin(∠ B1A1C1)) / B1C1. Значит угол ∠ B2С2A2 = ∠ B1С1A1. 2. Соответственно, оставшийся угол A1B1C1 = A2B2C2 (следствие из суммы углов в треугольнике). 3. Теорема доказана! Если найдете ошибку в доказательстве - значит решите задачу ;) Partisan Re: Подсказка к решению или Как показать, что теорема неверна. // Problem 1710. Boris, You Are Wrong! 23 Jun 2009 19:15 Wrong is decision in punct 1. I don't pusblish it, because it will be serious prompting. GhostMaster I dont't know why~~ [2] // Problem 1710. Boris, You Are Wrong! 4 Apr 2009 15:25 i mean if: AB<=BC or <ACB=90' or <BAC>90' then YES miss something? baiqi2piao Re: I dont't know why~~ // Problem 1710. Boris, You Are Wrong! 22 Apr 2009 19:34 if <BAC>90' then AB<=BC is always true Edited by author 22.04.2009 19:34 Edited by author 22.04.2009 19:34 svr Re: I dont't know why~~ // Problem 1710. Boris, You Are Wrong! 29 May 2009 09:52 (AB<=BC) || (BCA==90) || (BAC>=90) verify in int and if No 1001 ways for approximating calculations after PS: It is possible to make mistake about ==90 ABC==90 - May be! and it is test 26 Some time I was under influence of the fact that in 90-triangles for equality is enought 2 elements. Also it is interesting that special cases should verified under integer considerations all times because numeric methods are bad near this cases due big error multiplicators. Edited by author 31.05.2009 09:41 Programmer 1710 WA5.(+) [1] // Problem 1710. Boris, You Are Wrong! 4 Apr 2009 21:29 What is this test? Oleg Strekalovsky [Vologda SPU] Re: 1710 WA5.(+) // Problem 1710. Boris, You Are Wrong! 18 May 2009 13:03 I don't know what is this test's but I use some things: 1.Coordinate's shift to (0,0) 2.Checking: Angle(a,c,b)==90 Angle(a,b,c)>=90 Pay Attention to: VectorProduct(ac1,ac)>0, where c - is old C, c1 - new position of C Good Luck.
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