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Discussion of Problem 1458. War GamesIsabelle Lightray *~ Wow // Problem 1458. War Games 20 Nov 2018 17:14 Very fun and interesting problem. Although, before solving it I wrote a playable version, which was pretty hard to solve by hand (brain). The problem itself isn't that hard. You don't need any deep mathematical knowledge. Just think about what the move (cross xor) means and find its relation to consequent moves player can make. It's then pretty easy to formulate several theorems that let you write an O(n^2) solution. Alexander Samal WA#1 [1] // Problem 1458. War Games 4 Oct 2009 21:38 Help me, pls... Alexander Samal No subject // Problem 1458. War Games 25 Oct 2009 13:35 I m sure I have right solution, but I always get WA#1... Can anybody tell me what is test #1? PSV Gimme some ideas [11] // Problem 1458. War Games 4 Jul 2006 16:25 I can't understand how can it take 1 sec to solve for N = 1000 My biggest ideas is something like a system of equations by modulo 2, but ... Some hints please... PSV Please [10] // Problem 1458. War Games 5 Jul 2006 05:49 Please one small pour hint PSV Re: Please [9] // Problem 1458. War Games 7 Jul 2006 00:24 Please. I still have any ideas. May be finding of circles? WinTokk Re: Please [8] // Problem 1458. War Games 8 Jul 2006 19:31 linear module equations will work. try to rewrite it into a simpler form and you will achieve it! SPIRiT Where can I read about solving linear module equations?(+) [7] // Problem 1458. War Games 27 Sep 2007 21:11 I found a lot of material about modular arithmetic itself, but nothing about systems of equations modulo 2. There is a problem 1042 that I solved using an intuitive algo. But I don't have any materials about those kind of problems... Any links in Internet are available. svr Re: Where can I read about solving linear module equations?(+) [6] // Problem 1458. War Games 27 Sep 2007 21:49 I haven't AC but sure that 1458 is a problem with great mathematical background. In matrix language Sulman command is equal to transformation of tipe A[j]*B*A[k] where A[j]=diag[1,1,1,...,-1,1,1,1,1..] So, read about minimal step of transformations to standard form. Also, sequence of such transformation is code for arbitrary 0-1 matrix. Sure that authors create the problem during reading about 0-1 matrix, transformations and coding. KAJIAIII Re: Where can I read about solving linear module equations?(+) [5] // Problem 1458. War Games 27 Sep 2007 22:20 You're A LOOSER.I've done this program to 1 minute!!! svr Re: Where can I read about solving linear module equations?(+) [1] // Problem 1458. War Games 27 Sep 2007 22:45 Each has It's own way and all of us are training to contests. But even after you words the problem does't seem to me as simple. Often such quick solutions depend on temporary weakeness of tests. svr Re: Where can I read about solving linear module equations?(+) // Problem 1458. War Games 11 Jan 2009 11:29 Ac after some period! I did'n beleve that O-1 equation method can help. We have 10^6 unknowns and O(10^18) Gauss. But I had expierence for large systems with itteration method(as for Puasson eqution) and this method works here. But after I understood that the matrix of the system is nilpotent because nature of smoothing operator and itteration method has right foundation. Edited by author 10.02.2009 09:24 SPIRiT RE: program in one minute?(+) [2] // Problem 1458. War Games 28 Sep 2007 13:48 Well, then, where is your AC for this problem? You have no AC's at all... Denis Koshman Re: RE: program in one minute?(+) [1] // Problem 1458. War Games 29 Jul 2008 02:41 Just find a way to flip some cell without affecting others. It's easy for even N. Edited by author 03.08.2008 11:31 Fyodor Menshikov Re: RE: program in one minute?(+) // Problem 1458. War Games 10 Feb 2009 01:00 Denis Koshman wrote 29 July 2008 02:41 Just find a way to flip some cell without affecting others. Thanks! xj.ammo Timelimit at 11 with C++ [1] // Problem 1458. War Games 7 May 2006 16:34 Don't use IOSTREAM!!!! CSTDIO is much faster.. Denis Koshman Re: Timelimit at 11 with C++ // Problem 1458. War Games 29 Jul 2008 02:42 and simpler ;) ftc Hint [1] // Problem 1458. War Games 28 Jul 2008 11:47 May be it's obvious, but solution with no unnecessary moves is unique. I mean that if you get out from sequence pairs of equal moves and sort it you will get the same sequence. So you need to have 2 sequences: one transforming all to black and second - to white. Denis Koshman Re: Hint // Problem 1458. War Games 29 Jul 2008 02:39 A good hint (though, not so obvious for me). Sergey I am trying to solve problem with recursion methods. // Problem 1458. War Games 26 Aug 2006 04:39 Notice1: There is no differene in the order of operations. for example 1 0 than 2 3 is equal to 2 3 than 1 0 Notice 2: Same operation assumed 2*i times does not change the matrixxx. This is my thoughts. cqfwdghy how to output when no solution? [5] // Problem 1458. War Games 22 Apr 2006 13:24 how to output when no solution? Dmitry 'Diman_YES' Kovalioff No comments (-) // Problem 1458. War Games 22 Apr 2006 13:24 Victor Barinov (TNU) Solution is always exists (-) [3] // Problem 1458. War Games 27 Apr 2006 14:34 Sandro (USU) Re: Solution is always exists (-) [2] // Problem 1458. War Games 5 May 2006 08:48 What is the answer for test: 3 WWW WBW WWW ? GaLL [Tyumen SU] Re: Solution is always exists (-) [1] // Problem 1458. War Games 5 May 2006 15:15 N is even. Sandro (USU) Re: Solution is always exists (-) // Problem 1458. War Games 5 May 2006 21:21 Thanks! Orenburg SU 7 Very intersting problem [1] // Problem 1458. War Games 25 Apr 2006 01:49 I think 3 hours to got AC Zeva [USU] Re: Very intersting problem // Problem 1458. War Games 26 Apr 2006 20:06 I completely agree with you. Edited by author 26.04.2006 20:09
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