by **z666zz666z** » Tue Mar 05, 2013 1:29 pm

I know many people can not solve even a 9x9 sudoku (classic ones), some loves the 16x16, others the 25x25... the best is a 27x27 for doing it while walking, footing, etc...

But that ones are too fast to get solved with a paper and a pencil... i preffer bigger ones... like 50x50 or 128x128, etc...

I have allready done one of 10000x10000 (yes, a ten thousand numbers [from 0000 to 9999] on each row, column and block),... it took me a hole week to finish it manually with paper and a pencil, that was a chalenge!!!

After solving it, i create an application to auto-solve that kind ... for that one it tooks one one hour to finish...

I never used BackTraking at all, it is not needed for any Sudoku... all can be solved in direct way... it is just a matter of finding "conflicts" but with "boolean maths" they can be found very easy, so you can discard such numbers from the cell, best for computers to do such "maths" than for "humans", much faster than human brain.

The app i create used a 128GB SolidState Sata-III (500MB/s) disk as memory for solving it (trying to do it on RAM is not an option)... the needed RAM to hold the solution is 10000*10000*16bits so it is 2MB, it seems to be possible but it is not to hold the first non-solved state since it need 10000 times that (10000*10000*10000*16bits), so 20GB of RAM for just first step... best use directly a HDD instead or RAM to solve that... a huge file on a Ext4 partition and direct access to each Byte, it is not as fast as on RAM, but with a Sata-III SolidState 128GB HDD i get a Read speed of near 500MB per second in Full random access (SolidState, not a normal one), the half speed on writes.

I love that huge ones... i know i am mad... but now doing a 32x32 or a 50x50 (they takes no more than 1/2 hour up to no more than a hole hour...) have no sense for me to do such ones, not enough time to solve them.

So now, i am on 100x100 upto 250x250... they take me from one day up to two days per each one to solve them.

I think i will not do/create for the moment any other one, it is really madness,... just in case someone is asking it... how dare can i have it on paper? Simple... multiple A4 pages (near 1000 pages more or less)... as i said... Totally Madness.

Of course all of them with a dificulty level 10-12 of a maximun of 12... where you get to a state on where you must see if a candidate creates a conflict, je je.

Ah! i forgot to mention there is one person that has solved a 25000x25000 one [posible numbers for each cell from 00001 to 25000, such one did not have zero as a valid value, that makes a great difference on 'maths'] for that hyper-huge, used 62500 A4 papaer pages and a whole year!!! i know i am mad, but that one!!! how to call that?