Given a sequence of values v_n, replace each value with the first matching rule:

• if v = 0 -> 1
• If v has an even number of digits, split it (so v = 8675 becomes [86, 75])
• Otherwise, v -> v * 2024

Calculate how many elements are in the sequence after 25 iterations.

Given a heightmap (0 to 9), for each 0 count how many 9 you can reach on paths that only ever increase height by exactly 1 at a time. Sum these values.

Given a disk layout alternating between files and empty spaces, move all files as early on the disk is possible, splitting into multiple blocks. Return a checksum on the disk.

Alternating means: 23331 would mean a 2 block file, 3 empty, a 3 block file, 3 empty, and a 1 block file.

The checksum is the sum of file_id * block_index for all occupied blocks. File IDs are assigned sequentially on initial generation.

Given a grid with either open tiles (.) or towers (anything else), for each pair of towers, there is an antinode at each of the points that is 2x as far from one tower as the other. How many antinodes are there still within the bounds of the map?

Given a result and a list of numbers, determine if any combination of addition (+) and/or multiplication (*) using all the given numbers in order can return the result. Ignore order of operations.