Rubik’s Cube iPhone app

14 years ago

A couple of months ago I finished an article for PCPlus about algorithms for solving Rubik’s Cube. It’ll appear in issue 298 in September 2010.

As part of my research I came across this article and video on Wired about an iPhone app that helped you solve it and, more than that, solve it in a remarkably small number of moves (usually 20 or fewer) using Kociemba’s algorithm. The free app (called CubeCheater) was written by Eric Faller. Unfortunately it seems he didn’t request permission from Seven Towns (the current owners of the license to market Rubik’s Cube worldwide) and had to remove the app. (Aside: my editor at PCPlus, Alex Cox, obtained permission from them for me to write about Rubik’s Cube for the magazine before I ever put electronic pen to Microsoft Word paper.)

Bummer. I would have liked to try the app and written about it as well. But, no go, so I submitted the article and forgot about it.

Imagine my surprise when this weekend, I was perusing the App Store when I came across the official Rubik’s Cube iPhone app. Further imagine my surprise when I saw that said app had exactly the same solver function as CubeCheater. Not only that, but the same interface.

(Compare this to the interface shown in the video taken 18 months ago.) Interesting, no?

Anyway, I bought it ($4.99) to try it out. The only part of the app I was interested in was the Solver function where you input the state of a mixed-up cube and it solves it for you in as few moves as it can.

There is a cool feature where you input the faces using the camera rather than painting each cubelet with colors from the palette. You take a snapshot of the cube and the software works out the face’s grid and the colors in each cubelet.

For me and my particular cube this functionality is a complete and utter failure. The edge detection is pretty bad to begin with (hint: don’t try and fill the camera screen with the face like the image below, but make it occupy as much room as the image of the face above), but the color recognition just sucks. Here’s my white face (so called because it’s named after the center cubelet):

And here’s what the app thought it was:

There’s another problem which the app doesn’t address. For some unknown reason — perhaps because my cube is so old (I purchased it in 1979 before Ideal Toys got the original license to market the puzzle worldwide in 1980) — my cube center cubelets don’t follow the current standard positioning. I have red on the opposite side to white, not yellow. In fact, yellow and red are reversed on my cube, so, even if the camera input method worked, I’d have to fiddle with the colors anyway (wherever the app talks yellow, I have to think red, and vice versa).

OK, so given that for my physical cube I have to remember to switch yellow and red, does it work? Does it calculate a solution with a small number of moves? The answer is yes. It’s quite magical if you look at the cube after each move and see the colors slowly coming together.

I don’t particularly want to rate the app officially (after all, I haven’t tried the other parts of the app: solving a virtual cube on the screen with flicks of the finger, or the tutorial section), but I will admit to being very disappointed in the camera interface. Unlike this Sudoku Grab app, the AI in the Rubik’s Cube iPhone app is not that good at all.