I was pretty busy this weekend so I didn't have time to do the problems. I started on problem 15 but realized it would take me a lot of time, so I decided to go ahead and complete problems 16 and 17 and come back to 15 later.
This one took me a while because I was a little off on my first answers. I forgot to remove the first empty lines of the clay map, so I was 9 water tiles over the correct answer.
This problem was similar to the Marble Game on day 9, so I started with a solution similar to the one I used for that problem, using a linked list and having the two elves as linked list nodes that can move along the list. It worked fine for the first part of the problem, but started running pretty slow for the second part of the problem.
Nice little problem with a more complicated description but a somewhat simple solution.
This is the first problem that I still haven't an efficient way to solve the second part.