I’ve been spending quite a bit of time lately with my V-Cube. I’ve been fairly proficient at solving the first two layers of a cube for quite some time, but the last layer was always difficult, and I would end up needing to pull out my copy of “Speedsolving the Cube” to perform those last few algorithms. I’ve finally memorized them now, and I’m taking the time to solve my cube once a day to help commit them to memory
However, every time I think of Rubik’s Cube, I think about Rubik’s lesser known, but more fun (for me) puzzle, Rubik’s Tangle.
I got my first Rubik’s Tangle (#4 – one of the 5×5 versions) when I was in middle school, and while I found it to be a cool puzzle, it was beyond my young mind to fully grasp the intricacies of what I had. I remember taking a few shots at solving it, but I didn’t have any systematic method for doing so; instead, I spent more time just playing with the tiles.
When I learned to program and understood how to formulate more complicated algorithms (when I was in college), Rubik’s Tangle became a much more interesting puzzle. I began to understand more about the tiles themselves; I learned about the combinatorial nature of their design and that I had 24 unique tiles with one duplicate. I also discovered the rotational symmetry of the puzzle, and the obvious fact that if I could find one solution, there were actually eight solutions. Even though my algorithms were crude, I still remember waiting for hours and getting that first solution. Putting together my Tangle for the first time was amazing.
As I learned more about programming and algorithms, I was able to apply that knowledge to my Rubik’s Tangle solver and make it faster, cleaner, and more flexible. My code transformed from nested loops of structs utilizing string comparisons to classes with recursive functions utilizing integer comparisons. My algorithm utilized more puzzle structures of the Tangle to quickly prune unworkable options rather than naïve brute-force methods. My programs produced solutions in minutes and eventually seconds rather than hours.
Unfortunately, by the time that I knew enough to start thinking about the mythical 10×10 Tangle, the Rubik’s Tangle sets were so far out of print that I wasn’t able to get them (ebay didn’t have everything back then). Further, even though the Internet has everything, Rubik’s Tangle seems to have fallen mostly out of the public consciousness – even a google search turns up mostly internet hidey-holes that are almost 10 years old.
Still, Rubik’s Tangle will always be a favorite puzzle for me – it’s unique ideas and awesome mathematical concepts make for very interesting algorithm design, meta-reasoning, and even meta-puzzles to keep me thinking.