back to article This record-smashing robot solves a Rubik's Cube in 3.253 seconds

Forty years after the invention of the Rubik's Cube, the puzzle that's done more to induce finger injuries in youngsters than any games console, has been cracked at lightning speed by a Lego-built robot controlled by a Samsung S4 smartphone. The team behind the new Guinness World Record-winning robot consists of David Gilday …


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  1. Khaptain Silver badge

    Unbelievably wonderfull

    I learned to do the cube as a teenager many moons ago and never dropped under the 3 minute mark.

    Full kudos to this team for their prowess of being capable of solving the cube so quickly, their mastery of lego and their fantastic coding skills....

    I really admire these kinds of fun projects., must go out and buy myself some of that mindstorm stuff.

    1. Martin

      Re: Unbelievably wonderfull


      Yes, it's impressive the first time a Lego built machine + a phone solves the cube. I thought it was amazing when I saw the video for the first time last year. And it's quite something that it can do it under five seconds. But getting it down for 4.3 seconds to 3.5 (or whatever it is) is just improvements in technology - it's not anything new any more.

      There's also the point that a random setting may have a "best" solution which takes a certain number of moves. Another random setting may have a "best" solution which takes fewer moves. If the cube happens to be in the second setting, the robot will solve it more quickly. How do you tell whether you've merely got a relatively simple start position?

      Hence, the "meh" icon. It was impressive once. Now it's just more of the same.

    2. Cliff

      Re: Unbelievably wonderfull

      3.2 seconds to peel off all the labels and stick them back on is certainly impressive (that's how much patience I had with the cube...)

  2. Fuzz


    My understanding of these kinds of robots is that they don't actually solve the cube. They instead lookup the current state in a database of solutions. The robotics are pretty clever though. A couple of thoughts though, 1. would it be quicker to use 6 hands rather than 4, 2. are they still spinning the cube at the start and using the camera on the phone to read in the current state? If so wouldn't they be better with 6 cameras so they could scan all sides at the same time?

    1. Graham 24

      Re: solving?

      That would be a big database - according to Wikipedia, a Rubik's cube has 43,232,003,274,489,856,000 possible permutations.

      1. Anonymous Coward
        Anonymous Coward

        Re: solving?

        Ir's all Group Theory, so you wouldn't need to store every possible element.

        More likely it has a relatively small table of standard transformations to apply and it then determines a sequence of transformations to perform as it goes along.

        1. No, I will not fix your computer

          Re: solving?

          It's actually two groups (corners and sides) merging the two groups gives a maximum move solution of 20 moves, so (theoretically) the slowest "fast" solution is how long it takes to make 20 moves, and leaves the possibility of less than 20 moves if the random mix was advantageous (and opposite side moves in counter-rotation could be done at the same time), could even optimise the initial moves with partial information before the initial scan is complete.

          Sub 3 seconds should be possible, although not by me, being an armchair geek, I never actually do anything, I just comment one stuff I'm to stupid or lazy to do myself, well done guys!

          Best I managed was 57 seconds, and 4.33 for the revenge (but I did solve the revenge before there was any official world record recorded)

  3. A Non e-mouse Silver badge

    The robot demonstrates just how fast a Samsung Galaxy S4 can think

    To my mind, the speed of the phone's CPUs is not the impressive part. That high-speed robot made of Lego: Now that's the bit that impresses me.

    It would have have been nice if they'd captured it with a high(er) speed camera and then made a slow-mo video of it.

  4. Tom 7 Silver badge

    Robots Rubik Record

    lazy bastard journalists - you can surely add half a dozen other alliterative words to the title!

    Or where you overwhelmed by having content for a change?

  5. Longrod_von_Hugendong
    Thumb Up


    ARM Cpu's are really getting fast these days... but the killer on this is the speed that the lego can go... that is truly awesome!

  6. Anonymous Coward
    Anonymous Coward

    I'll be damned...

    ..if I'm going to invest in a bucket load of Lego Technic and a Galaxy S4 just so my teenage son can say he's finally solved the Rubik Cube..

    Back to reality, very impressive combo there, Lego and an S4 achieving this in seconds where I've met people who've never managed to complete the Rubik's Cube

    1. Roland6 Silver badge

      Re: I'll be damned...

      Invest in a bucket of Lego Technic certainly - it will keep you and your son amused while you wait - the 'app' isn't available for download yet...

  7. GreggS


    I blinked. What was it again?

  8. Bartlomiej Kochan

    brute force

    Slap on 6 x 9 coloured stickers simultaneously from all sides .

    It could be done under 1s I recon.

    That how them rubics are 'solved' for the first time in factories right ?

    With this black box approach it is the fastest method.

    If U want to save on stickers: analyze image first and

    only apply the 'mising' ones.

    Penguin... 'cos of the OS.

  9. Michael H.F. Wilkinson Silver badge
    Thumb Up

    Nice project

    This kind of project is great to get kids enthusiastic for computer science at an early age.

  10. FartingHippo

    "machines make our efforts in this field look puny"


    5.55 seconds is still amazing - but even that could have been a fluke where everything fell into place. Truly amazing is Feliks Zemdegs averaging 6.54 seconds over 5 runs.

    Having to rely on set algorithms and muscle-memory also means that "puny humans" have to do far more moves per second than the robot. Watch the first 10 seconds of this.

    1. James Hughes 1

      Re: "machines make our efforts in this field look puny"

      No, what is amazing is the guy who can look at 20 rubiks cubes, put on a blindfold, then do them all., 8 minutes in.

  11. Nick Kew Silver badge

    Sloppy timeline

    Forty years?

    When I first encountered the "magic cube" in 1979[1] the construction was so primitive you'd often take more than 3.whatever seconds just to un-jam it and make a single move. It neither acquired the "Rubik" name nor appeared in the shops until 1980.

    Is there a Bah Humbug icon for old farts?

    [1] I remember the occasion well. It was a two week summer pre-course for those of us who had just left school and were about to go up to Cambridge. John Conway, the brilliant mathematician and showman, teased us with it in an extremely entertaining lecture.

  12. Roland6 Silver badge

    Not quite as impressive as the other Lego Rubik cube solver...

    At the Big Bang Show the team was also showing off a lego robot and smartphone combination that was solving a 10x10x10 Rubik's cube in minutes.

    Video clip:

  13. Camilla Smythe

    One Camera?

    If you look at the position of the Phone then in effect it only has sight of one face. Presumably as a result it has to take a few trial spins to locate/relocate and store the position of the separate bricks before it can steam on. In fact you can see it do this. The display begins by showing just the top face and then after a few moves, whole rotations to map the cube, converts to a three-d representation. In fact once it has that data in place it probably isn't looking any more. Is that in the rules and representative of what a human is restricted to? Perhaps academic however the solution would be quicker if.. blah.. blah.. etc.

  14. Anonymous Coward
    Anonymous Coward

    What I want to see ..

    .. is this thing chewing on a Rubik's cube that has one bit flipped over.

    Being the evil sort, I recall coming up with a flip of one part that rendered the cube unsolvable so that it would frustrate the heck out of those speed cubers. It would be interesting to see how it would fail: software crash, or forever rotating. Just curious.

  15. Proud Father

    Ah good old school days..

    I remember being in a competition at school. Timed Rubik cube solving.

    I came second with 1min 10sec to complete, first place was 58sec.

    1. Martin

      Re: Ah good old school days..

      But how did you learn to do it - and can you still do it?

      I originally solved the cube without recourse to any instructions - took me a couple of months. (My first ever success was a fluke, where I did the first two layers and the third just appeared correctly - to my total astonishment.) But as a result, I have those slow but reliable algorithms fixed in place in my mind (and muscle memory!). I can still solve it now - but it probably takes me 3-5 minutes - and using my algorithms, I doubt if it could be done more quickly than two minutes.

      But those algorithms work, and I suspect I'll never forget how to do it now. It's still a good trick for impressing your kids and their friends.

      1. Proud Father

        Re: Ah good old school days..

        Remember the 'Vietnamese boat people'? My family was friends with some of the refugees that settled in our town. On them was a young guy, probably a little older than me. Highly intelligent, he showed me lots of ways to solve Rubik's cube.

        Now? No chance, not a clue. School is some 30+ years ago now :(

      2. Khaptain Silver badge

        Re: Ah good old school days..

        I'm in the same boat as Martin, more than 30 years ago the "algorithms" was learded, some self taught, some shared, were imprinted into my mind. I can still do the cube without really thinking about it, I do need to look at it several times though.. unlike the guy doing the 20 cubes ... whilst blindfolded....

        Always the same method.

        Top Face - No importance as to whether the corners or middle are inserted first. This is the easist section - very little, if any, thought required.

        Middle row

        Algorithm reverses dependant on the original orientation of the piece to be inserted ( to the left or to the right ). Only one algorithm required.

        Bottom row - -

        One algorithm for swapping 3 middle pieces at a time. ( all pieces rotate to the left or right as required)

        One algorithm for inverting middle pieces if upside down.


        One algorithm for swapping 2 corner piece positions until all pieces in correct positions..

        Last and final algorithm for inverting all corner pieces to their correct orientation, the positions dont shift .


        1. DougS Silver badge

          Re: Ah good old school days..

          I learned those same algos, and with them was able to average about 30 seconds to solve, but I don't remember any of them anymore. But I still remember the patterns for Pac Man. Funny what sticks with you, and what you forget...

  16. Pete4000uk

    Best part is...


  17. Winkypop Silver badge

    "Forty years after the invention of the Rubik's Cube"

    Old, I'm old!

  18. Brian Morrison

    These chaps have dedication!

    Well done to them both, it's great to see such single-mindedness.

    It's a long time since I remember seeing David and family happily playing with Mindstorms robots on the living room floor, glad to see that all that coding has achieved something really useful!

  19. ATeal
    Thumb Down

    Crap video

    It is like a game advert, tiny snippet of game related stuff with titles at the start and end. Totally worth watching.

    That aside, I can only wonder why the "ARM" part is important, Rubik(like) puzzles are problems in the P domain! If anything use the lego logo! You couldn't do that with say Megablocks!

    Just to clarify I love Samsung hardware, hate that crap they put on it (Cyanogenmod FTW) I really do think "ARM" is pointless here.

  20. MooseNC

    Well, this is good news.

    Now when the Googlenators track me down with the help of the hovering AmazOMG drones, they can rip me apart faster than before.


    Thought for a while that I would have to suffer for 5.55 seconds before death by the hands of our soon-to-be metal overlords.

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