Bedlam Cube Solved (ALL 19,186 solutions)

scottkurowski.com

35 points·kristianp··7 comments

This is not a new solution. This article is from 2008 or earlier.

https://web.archive.org/web/20080704123725/http://scottkurow...

We got one of those years ago. I had already written a Sudoku solver using Knuth's Dancing Links, so I modified it to find the Bedlam solutions. The program worked mostly but gave duplicates for some of the solutions. It was also fun to develop solution search criteria for placing the pieces, e.g. to get the reds all down one corner.

Haha that's funny, the person that introduced me to programming set me the bedlam cube as a challenge. I used dancing links and later on adapted it to sudoku!

> The software search completed in 86 hours on my old 2 GHz Pentium 4 laptop.

This is an old article. Would be fun to see someone write a multithreaded solver and let it run on a modern CPU.

Or, make it a LeetCode problem. Within 24 hours you’d have someone come up with a mind boggling hyper-optimized solution using tricks you didn’t even know existed.

I compiled the code with minor changes on my M3 Macbook Air and it found the 19186 unique solutions in about 3hrs 15min, so ~9.2X speedup (over the 30hrs stated in the post). Would indeed be interesting to see how fast you can go with some optimization.

EDIT: I forgot to add -O3 the first time, with that the time to 19186 drops to under and hour, so over 30X speedup.

Nice to see that this has surfaced again, it disappeared just about the same time as I was trying to solve it myself (https://simonekstrom.se/2023/12/17/puzzle-cube.html).

I refuse to enter the website until it implements https. A free Let's Encrypt certificate will do. Otherwise I don't even know if I'm reading what the author published on the site, or what a man-in-the-middle provided me.

Reply on news.ycombinator.com