2024(9): solve part 1 and some

Committed on the 8th of January, 2025, so I do not know what I did.

2024/09/README.md

@@ -58,3 +58,24 @@ The final step of this file-compacting process is to update the _filesystem chec
 Continuing the first example, the first few blocks' position multiplied by its file ID number are `0 * 0 = 0`, `1 * 0 = 0`, `2 * 9 = 18`, `3 * 9 = 27`, `4 * 8 = 32`, and so on. In this example, the checksum is the sum of these, _`1928`_.
 
 <span title="Bonus points if you make a cool animation of this process.">Compact the amphipod's hard drive</span> using the process he requested. _What is the resulting filesystem checksum?_ <span class="quiet">(Be careful copy/pasting the input for this puzzle; it is a single, very long line.)</span>
+
+### Part Two
+
+Upon completion, two things immediately become clear. First, the disk definitely has a lot more contiguous free space, just like the amphipod hoped. Second, the computer is running much more slowly! Maybe introducing all of that [file system fragmentation](https://en.wikipedia.org/wiki/File_system_fragmentation) was a bad idea?
+
+The eager amphipod already has a new plan: rather than move individual blocks, he'd like to try compacting the files on his disk by moving _whole files_ instead.
+
+This time, attempt to move whole files to the leftmost span of free space blocks that could fit the file. Attempt to move each file exactly once in order of _decreasing file ID number_ starting with the file with the highest file ID number. If there is no span of free space to the left of a file that is large enough to fit the file, the file does not move.
+
+The first example from above now proceeds differently:
+
+    00...111...2...333.44.5555.6666.777.888899
+    0099.111...2...333.44.5555.6666.777.8888..
+    0099.1117772...333.44.5555.6666.....8888..
+    0099.111777244.333....5555.6666.....8888..
+    00992111777.44.333....5555.6666.....8888..
+    
+
+The process of updating the filesystem checksum is the same; now, this example's checksum would be _`2858`_.
+
+Start over, now compacting the amphipod's hard drive using this new method instead. _What is the resulting filesystem checksum?_

2024/09/part1.py

@@ -19,7 +19,7 @@ def disk_map_to_blocks(disk_map: str) -> list:
 
 	return blocks
 
-def move_ltr_to_empty_space(blocks: list) -> str:
+def move_blocks_ltr_to_empty_space(blocks: list) -> str:
 	left = 0
 	right = len(blocks) - 1
 
@@ -53,7 +53,7 @@ if __name__ == "__main__":
 		print("Blocks:")
 		print(blocks)
 
-	result = move_ltr_to_empty_space(blocks)
+	result = move_blocks_ltr_to_empty_space(blocks)
 
 	if verbose:
 		print()