Long, long ago I came up with a text search algorithm while working on PCxRef to help technical sales support at IBM. My first approach using a naive string search took about 30 seconds on a PC. My algorithm got it down to the speed of disk access.

Basically I precomputed a table of masks and used the XLAT instruction in a very tight loop to fly though all the product descriptions for everything IBM offered back around 1983. I could accommodate case insensitivity and single character wildcards.

The test search was always "dos tech ref" to find the IBM DOS Technical reference manual.

I'd say nothing has beaten the association rules + graph search I did for my thesis about restocking an automated picking machine in a warehouse (https://github.com/aleda145/product_allocation_aframe)

code: https://github.com/aleda145/product_allocation_aframe/blob/m...

I'm not proud of this code, but it yielded 0.2% better result than the naive approach!

An auto-arrange feature for a LabVIEW/ComfyUI type DAG programming language. Could take a program with hundreds of nodes and edges and arrange them nicely so none of the lines intersected and blocks were grouped logically.