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.

You are given a grid of walls (#), floors (.), and a guard (^, initially facing up/north). The guard walks forward until they run into a wall at which point they turn right. How many tiles does the guard reach before leaving the map.