A and B were roughly the same difficulty.

So in my first year in university, in my intro DSA class, we learned A*. Have I learned any other ways to search since? Not really. So I used A* here.

It took way longer than it should have to solve, which I blame on my ongoing illness. The main sticking point was that I implemented a class to represent the search state, and since I was going to use it as a key to a map, I implemented a hashcode for it. The rest of the A* code freely flowed from my brain (really the wikipedia pseudocode).

Cue like 40 mins plus of wondering how the test input was searching over millions of states, wondering if I’d fucked up the A* implementation, wondering if the problem was too big for A*, and wondering if it was finally time to take a days break from all the aoc nonsense.

Anyway at some point I realised I forgot to implement the corresponding equals method to my hashcode. Once I had that my code ran in seconds and everything was fine. This sickness is the worst!!!