All the problems are now completed.

This is the first problem for which I had to get a solution online for the second part.

Another problem that had me looking at my wrong answer for a while not understanding what was happening. This time I realized that a group with negative units could attack (because it had been killed previously in the round).

The first part for this problem was pretty straight forward, simply calculate the erosion level for each region and transform that into region types before summing the ones in the desired region. Since you're multiplying big integers, at some point there be overflow, but since you're also doing modulo operations, you can work with modulo arithmetic from the start and only conserve the remainder when computing the erosion level of a region.

Back to assembler for this one.