# Optimal Solvers



## loid (Mar 10, 2010)

Hi!

I am making a demo video for the Nintendo DS game Rubik's World where I solve a 2x2x2, 3x3x3 and 4x4x4 cube "as fast as possible"

I have found a couple of tools for finding optimal solutions, but I was hoping someone here might have some suggestions as well. In particular for 4x4x4. Also, I am most interested in ones that use a "quarter turn" metric when calculating the optimal solution, though any suggestions are much appreciated.


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## qqwref (Mar 10, 2010)

Unfortunately there is no program which can calculate an optimal solution for the 4x4x4 in a reasonable amount of time (unless the position is less than about 12 moves from solved, which is very very unlikely). There is simply not enough computational power.


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## loid (Mar 10, 2010)

What's an unreasonable about of time? I'm willing to let it sit for days...


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## Feryll (Mar 10, 2010)

Use CubeExplorer for the 3x3x3, and use just the corners to simulate a 2x2x2, and I heard of a software about solving the 4x4x4 quickly, but not optimally. It solves the individual steps to solving it optimally, but an optimal solution doesn't always solve it using those steps, so it is just a short, but not the shortest, solution.


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## qqwref (Mar 10, 2010)

loid said:


> What's an unreasonable about of time? I'm willing to let it sit for days...



How about billions of years?  Brute-forcing an optimal solution is essentially impossible and I don't think there is any better way to do it at the moment.


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## iSpinz (Mar 10, 2010)

qqwref said:


> loid said:
> 
> 
> > What's an unreasonable about of time? I'm willing to let it sit for days...
> ...


Would a 4x4 solver that would do it like centers, edges, optimal 3x3 be quicker?


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## Zarxrax (Mar 10, 2010)

Well, if one isn't interested in completely optimal solutions, I think it would certainly be possible to break it into steps, such as optimal solution for centers, then optimal solution for edges, then optimal solution for 3x3x3 step.


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## loid (Mar 11, 2010)

Feryll said:


> Use CubeExplorer for the 3x3x3, and use just the corners to simulate a 2x2x2, and I heard of a software about solving the 4x4x4 quickly, but not optimally. It solves the individual steps to solving it optimally, but an optimal solution doesn't always solve it using those steps, so it is just a short, but not the shortest, solution.



I'm thinking this is the software you heard of: http://www.speedsolving.com/forum/showthread.php?p=308637

I also used the 4x4x4 solver in Rubix but it seemed to be less optimal. I am also planning to use Rubix for the 2x2x2 solution, and Cube Explorer and something called optiqtm for the 3x3x3 (optiqm uses the quarter turn metric and accepts Cube Explorer files as input).

Thanks for all the help folks! I'll post a link to my video when it is up.


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## Micael (Mar 11, 2010)

Do you just want to show a single "solve" with very few move in your video? If so, why not just doing an inverse scramble (like 30 moves)... Or may be I don't understand what you want to do?


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## loid (Mar 11, 2010)

It's a video game that gives you a random cube, so I wouldn't know how to reverse it (unless I could dig into the code, which is kind of outside the scope of my ability at this point).

Good idea though!


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## loid (Mar 12, 2010)

Sorry to double post, but here's a preview with the first two cubes:

http://dl.dropbox.com/u/1665523/rubiksnew.avi

You need the h264 codec installed to play it. If you have trouble playing try installing ffdshow (it's pretty awesome in general): http://sourceforge.net/projects/ffdshow/


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## Zarxrax (Mar 15, 2010)

loid said:


> You need the h264 codec installed to play it. If you have trouble playing try installing ffdshow (it's pretty awesome in general): http://sourceforge.net/projects/ffdshow/


The original ffdshow is horribly outdated (six years old!) and should not be used. FFDShow tryouts is an updated and stable version.


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## loid (Apr 2, 2010)

Well my software suggestions notwithstanding, here's the finished video. Thanks again for all y'all's help!

http://www.youtube.com/watch?v=p8h6ilJ9dso


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## joey (Apr 2, 2010)

haha awesome


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## Kirjava (Apr 2, 2010)

ahaha, that was so cool. Nothing less than optimal would be good enough for TAS.


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## giantcuber (Apr 3, 2010)

loid said:


> Well my software suggestions notwithstanding, here's the finished video. Thanks again for all y'all's help!
> 
> http://www.youtube.com/watch?v=p8h6ilJ9dso



That's awesome!!!


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