advent-of-code/2022/day7.py
Mikaël Capelle 8a0412f926 Clean 2022.
2023-12-09 09:54:53 +01:00

81 lines
2.0 KiB
Python

import sys
from pathlib import Path
lines = sys.stdin.read().splitlines()
# we are going to use Path to create path and go up/down in the file tree since it
# implements everything we need
#
# we can use .resolve() to get normalized path, although this will add C:\ to all paths
# on Windows but that is not an issue since only the sizes matter
#
# mapping from path to list of files or directories
trees: dict[Path, list[Path]] = {}
# mapping from paths to either size (for file) or -1 for directory
sizes: dict[Path, int] = {}
# first line must be a cd otherwise we have no idea where we are
assert lines[0].startswith("$ cd")
base_path = Path(lines[0].strip("$").split()[1]).resolve()
cur_path = base_path
trees[cur_path] = []
sizes[cur_path] = -1
for line in lines[1:]:
# command
if line.startswith("$"):
parts = line.strip("$").strip().split()
command = parts[0]
if command == "cd":
cur_path = cur_path.joinpath(parts[1]).resolve()
# just initialize the lis of files if not already done
if cur_path not in trees:
trees[cur_path] = []
else:
# nothing to do here
pass
# fill the current path
else:
parts = line.split()
name: str = parts[1]
if line.startswith("dir"):
size = -1
else:
size = int(parts[0])
path = cur_path.joinpath(name)
trees[cur_path].append(path)
sizes[path] = size
def compute_size(path: Path) -> int:
size = sizes[path]
if size >= 0:
return size
return sum(compute_size(sub) for sub in trees[path])
acc_sizes = {path: compute_size(path) for path in trees}
# part 1
answer_1 = sum(size for size in acc_sizes.values() if size <= 100_000)
print(f"answer 1 is {answer_1}")
# part 2
total_space = 70_000_000
update_space = 30_000_000
free_space = total_space - acc_sizes[base_path]
to_free_space = update_space - free_space
answer_2 = min(size for size in acc_sizes.values() if size >= to_free_space)
print(f"answer 2 is {answer_2}")