99 lines
3.1 KiB
Python
99 lines
3.1 KiB
Python
from __future__ import annotations
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from dataclasses import dataclass
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from typing import ClassVar, Iterator
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from advent.parser.parser import P
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day_num = 5
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def part1(lines: Iterator[str]) -> str:
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crane = Crane.parse(lines, False)
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crates = crane.perform_all_moves()
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return Crane.top(crates)
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def part2(lines: Iterator[str]) -> str:
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crane = Crane.parse(lines, True)
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crates = crane.perform_all_moves()
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return Crane.top(crates)
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@dataclass(slots=True, frozen=True)
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class Move:
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amount: int
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frm: int
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to: int
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amount_parser: ClassVar[P[int]] = P.snd(P.string("move "), P.unsigned())
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from_parser: ClassVar[P[int]] = P.snd(P.string(" from "), P.unsigned())
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to_parser: ClassVar[P[int]] = P.snd(P.string(" to "), P.unsigned())
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move_parser: ClassVar[P[tuple[int, int, int]]] = P.seq(amount_parser, from_parser, to_parser)
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@staticmethod
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def parse(line: str) -> Move:
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amount, frm, to = Move.move_parser.parse(line).get()
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return Move(amount, frm - 1, to - 1)
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def do_move(self, crates: list[str], as_9001: bool) -> list[str]:
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"""
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Moves the given crates by the provided move. Will fail if there are not enough crates
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in the from stack
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"""
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if as_9001:
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crates[self.to] += crates[self.frm][-self.amount:]
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else:
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crates[self.to] += crates[self.frm][-self.amount:][::-1]
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crates[self.frm] = crates[self.frm][:-self.amount]
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return crates
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@dataclass(slots=True, frozen=True)
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class Crane:
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stacks: list[str]
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moves: list[Move]
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is_9001: bool
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crate_parser: ClassVar[P[str | None]] = P.either(
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P.any_char().in_brackets(), P.string(" ").replace(None))
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crate_row_parser: ClassVar[P[list[str | None]]] = crate_parser.sep_by(P.is_char(' '))
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@staticmethod
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def parse_crate_row(line: str) -> list[None | str] | None:
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return Crane.crate_row_parser.parse(line).get_or(None)
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@staticmethod
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def parse_drawing(lines: Iterator[str]) -> list[str]:
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stacks: list[str] = []
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for line in lines:
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crate_row = Crane.parse_crate_row(line)
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if crate_row is None:
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next(lines) # Empty line
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return stacks
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if len(stacks) < len(crate_row):
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stacks += [""] * (len(crate_row) - len(stacks))
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for stack_num, crate in enumerate(crate_row):
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if crate is not None:
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stacks[stack_num] = crate + stacks[stack_num]
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raise Exception("Can never happen")
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@staticmethod
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def parse(lines: Iterator[str], is_9001: bool) -> Crane:
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drawing = Crane.parse_drawing(lines)
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moves = [Move.parse(line) for line in lines]
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return Crane(drawing, moves, is_9001)
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@staticmethod
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def top(crates: list[str]) -> str:
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""" Lists the last item in the given stacks. Fails if any stack is empty """
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return ''.join(stack[-1] for stack in crates)
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def perform_all_moves(self) -> list[str]:
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stacks = self.stacks
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for move in self.moves:
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stacks = move.do_move(stacks, self.is_9001)
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return stacks
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