83 lines
2.1 KiB
Python
83 lines
2.1 KiB
Python
# -*- encoding: utf-8 -*-
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import sys
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from pathlib import Path
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lines = sys.stdin.read().splitlines()
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# we are going to use Path to create path and go up/down in the file tree since it
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# implements everything we need
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#
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# we can use .resolve() to get normalized path, although this will add C:\ to all paths
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# on Windows but that is not an issue since only the sizes matter
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#
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# mapping from path to list of files or directories
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trees: dict[Path, list[Path]] = {}
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# mapping from paths to either size (for file) or -1 for directory
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sizes: dict[Path, int] = {}
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# first line must be a cd otherwise we have no idea where we are
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assert lines[0].startswith("$ cd")
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base_path = Path(lines[0].strip("$").split()[1]).resolve()
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cur_path = base_path
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trees[cur_path] = []
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sizes[cur_path] = -1
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for line in lines[1:]:
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# command
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if line.startswith("$"):
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parts = line.strip("$").strip().split()
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command = parts[0]
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if command == "cd":
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cur_path = cur_path.joinpath(parts[1]).resolve()
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# just initialize the lis of files if not already done
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if cur_path not in trees:
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trees[cur_path] = []
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else:
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# nothing to do here
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pass
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# fill the current path
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else:
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parts = line.split()
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name: str = parts[1]
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if line.startswith("dir"):
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size = -1
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else:
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size = int(parts[0])
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path = cur_path.joinpath(name)
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trees[cur_path].append(path)
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sizes[path] = size
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def compute_size(path: Path) -> int:
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size = sizes[path]
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if size >= 0:
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return size
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return sum(compute_size(sub) for sub in trees[path])
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acc_sizes = {path: compute_size(path) for path in trees}
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# part 1
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answer_1 = sum(size for size in acc_sizes.values() if size <= 100_000)
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print(f"answer 1 is {answer_1}")
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# part 2
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total_space = 70_000_000
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update_space = 30_000_000
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free_space = total_space - acc_sizes[base_path]
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to_free_space = update_space - free_space
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answer_2 = min(size for size in acc_sizes.values() if size >= to_free_space)
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print(f"answer 2 is {answer_2}")
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