110 lines
3.5 KiB
Python
110 lines
3.5 KiB
Python
from __future__ import annotations
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from dataclasses import dataclass, field
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from typing import Iterator
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day_num = 7
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def part1(lines: Iterator[str]) -> int:
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return Directory.parse(lines).get_maxed_size(100_000)
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def part2(lines: Iterator[str]) -> int:
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directory = Directory.parse(lines)
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return directory.get_min_delete_size(70_000_000, 30_000_000)
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@dataclass(slots=True)
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class Directory:
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name: str
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parent: Directory | None
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subdirs: list[Directory] = field(default_factory=list)
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files: list[tuple[str, int]] = field(default_factory=list)
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size: int | None = None
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def cd_into(self, name: str) -> Directory:
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"""
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Returns the named sub directory or .. for parent
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May fail if unkown subdirectory - or already in root
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"""
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if name == "..":
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if self.parent is None:
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raise Exception('Already at root Directory')
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return self.parent
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for sub in self.subdirs:
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if sub.name == name:
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return sub
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raise Exception(f"Could not find subdir {name}")
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def add_directory(self, name: str):
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""" Adds the named directory."""
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self.subdirs.append(Directory(name, self))
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def add_file(self, name: str, size: int):
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""" Adds the given file and size """
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self.files.append((name, size))
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def get_size(self) -> int:
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""" returns the size of this directory including all subdirectories """
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if self.size is None:
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self.size = (sum(size for _, size in self.files)
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+ sum(sub.get_size() for sub in self.subdirs))
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return self.size
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def get_all_directories(self) -> Iterator[Directory]:
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""" Returns an iterator of all subdirectories """
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for sub in self.subdirs:
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yield from sub.get_all_directories()
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yield self
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def get_maxed_size(self, threshold: int) -> int:
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""" Returns the sum of all sizes of subdirectories, that are below the given threshold"""
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return sum(size for size in
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(dir.get_size() for dir in self.get_all_directories())
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if size <= threshold)
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def get_min_delete_size(self, disk_size: int, space_needed: int) -> int:
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"""
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Returns the size of the smallest directory that must be removed to created the free space
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given as a parameter and the given disk size
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#"""
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unused = disk_size - self.get_size()
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minimum: int | None = None
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for dir in self.get_all_directories():
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size = dir.get_size()
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if unused + size >= space_needed and (minimum is None or minimum > size):
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minimum = size
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if minimum is None:
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raise Exception("Could not find large enough directory to remove")
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return minimum
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@staticmethod
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def parse(lines: Iterator[str]) -> Directory:
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line = next(lines)
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if line != '$ cd /':
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raise Exception(f"Illegal first line: {line}")
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root = Directory('/', None)
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current = root
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for line in lines:
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match line.split():
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case ['$', 'cd', name]:
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current = current.cd_into(name)
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case ['$', 'ls']:
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pass
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case ['dir', name]:
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current.add_directory(name)
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case [size, name]:
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current.add_file(name, int(size))
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case _:
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raise Exception(f"Could not parse line: {line}")
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return root
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