The HLP is a question in Minecraft redstone that asks how to optimally convert a hex line into a desired set of signal strength outputs. Because I am a massive nerd, this problem piqued my interest greatly.

There is no "nice" algorithm, since a subset of the HLP is equivalent to sorting by prefix reversals, which has been proven to be NP-hard. As such, brute force is the only option, while desperately clawing at optimizations to save time.

I coded the algorithm in C to maximize speed, and implemented a novel way to store HLP functions to minimize space needed for caching to the theoretical minimum. This new approach plus other optimizations makes it surprisingly fast.

While not perfect, I like my algorithm, if for no other reason than because I made it. The HLP is a really interesting problem to work on, even if a bit niche!