92 lines
2.7 KiB
Python
92 lines
2.7 KiB
Python
from __future__ import annotations
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from dataclasses import dataclass
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from typing import Iterator
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day_num = 9
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def part1(lines: Iterator[str]) -> int:
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lst = [Command.parse(line) for line in lines]
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return Command.walk(lst, 2)
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def part2(lines: Iterator[str]) -> int:
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lst = [Command.parse(line) for line in lines]
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return Command.walk(lst, 10)
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@dataclass(frozen=True, slots=True)
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class Point:
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x: int
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y: int
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@staticmethod
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def parse_direction(char: str) -> Point:
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""" Parses the given direction to a Point. May raise if invalid """
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match char:
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case 'R':
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return Point(1, 0)
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case 'U':
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return Point(0, 1)
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case 'L':
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return Point(-1, 0)
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case 'D':
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return Point(0, -1)
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case _:
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raise Exception(f"Unkown Direction: {char}")
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def add(self, other: Point) -> Point:
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return Point(self.x + other.x, self.y + other.y)
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def sub(self, other: Point) -> Point:
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return Point(self.x - other.x, self.y - other.y)
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def is_unit(self) -> bool:
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""" return true, if this discribes any point (diagonally) adjacent to the origin"""
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return abs(self.x) <= 1 and abs(self.y) <= 1
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def as_unit(self) -> Point:
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""" Compresses this Point to a point with unit components """
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def unit(num: int) -> int:
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return 0 if num == 0 else num // abs(num)
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return Point(unit(self.x), unit(self.y))
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def step_to(self, other: Point) -> Point | None:
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diff = other.sub(self)
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if diff.is_unit():
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return None
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return self.add(diff.as_unit())
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@dataclass(frozen=True, slots=True)
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class Command:
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dir: Point
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steps: int
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@staticmethod
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def parse(line: str) -> Command:
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""" Parse a command line. My raise exception if the was an illegal line"""
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match line.split():
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case [dir, steps]:
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return Command(Point.parse_direction(dir), int(steps))
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case _:
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raise Exception(f"Illegal line: {line}")
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@staticmethod
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def walk(lst: list[Command], rope_length: int):
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""" Walks the whole rope in Planck length steps """
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rope = [Point(0, 0)] * rope_length
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visited = {rope[-1]}
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for command in lst:
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for _ in range(command.steps):
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rope[0] = rope[0].add(command.dir)
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for n in range(1, rope_length):
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moved_piece = rope[n].step_to(rope[n - 1])
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if not moved_piece:
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break
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rope[n] = moved_piece
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if n == rope_length - 1:
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visited.add(rope[n])
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return len(visited)
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