AoC Day 9 was a lesson in what works fantastic for the first part, fails miserably for the 2nd part. Its one of the frustrations but also challenges of AoC, where you only get half of the final requirements to start. The puzzle input you get is just a string of single digit numbers (i.e. 12345) The digits in the string go back and forth in what they represent. The first digit is the size of a file, followed by the size of free space between that file and the next file. So for my example above, I have a file that is one block big, followed by two free blocks. Followed by a file three blocks big, followed by four free blocks, finally followed by a five block file.

AoC Day 8 has us mapping interactions between items on a grid. The input is a large grid filled with mostly blank (“.”) spaces. However, across the grid are multiple “antennas” identified by the frequency that they are broadcasting (frequency is identified by an arbitrary letter or number). The challenge is to find interactions between the various antennas that are broadcasting on the same frequency.