There was one about piecing together data from multiple under-water sensors regarding the locations of mines or something. With the data being rotated in various orientations (in right angle increments) thus having to correlate the overlapping data items. I think it was 19. I wrote quite a log of code to brute force this:

https://www.kylheku.com/cgit/advent/tree/2021/19

Some people's solutions used some linear algebra libraries in ways I don't understand; one day I will revisit that.