https://adventofcode.com/2023/day/16

This is a pretty straight forward graph traversal of the state space. I represent nodes of the "graph" being searched as pairs of a location and a direction vector. At each step the location is used to look up the tile and the direction vector is used to compute reflections and splits.

Optimizations:

• Parallelize the search in part 2
• Only track seen states for beam splitters
• Count visited locations with an array instead of a Set
• Pack photon states into an Int to make seen set lookups faster

>>> :{
:main +
".|...\\....
|.-.\\.....
.....|-...
........|.
..........
.........\\
..../.\\\\..
.-.-/..|..
.|....-|.\\
..//.|....
"
:}
46
51