89 lines
2.3 KiB
Python
89 lines
2.3 KiB
Python
from dataclasses import dataclass
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from functools import cached_property
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from itertools import pairwise
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from textwrap import dedent
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from typing import Iterator, override
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from unittest import TestCase
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from more_itertools import ilen
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from puzzles._solver import Solver
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@dataclass
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class Report:
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levels: tuple[int, ...]
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@cached_property
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def deltas(self) -> tuple[int, ...]:
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return tuple(b - a for a, b in pairwise(self.levels))
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def is_gradual_monotonic(self) -> bool:
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sign = 1 if self.deltas[0] > 0 else -1
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return all(
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delta != 0 and delta / abs(delta) == sign and abs(delta) < 4
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for delta in self.deltas
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)
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def permute_dampened_variations(self) -> Iterator["Report"]:
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return (
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Report(self.levels[:i] + self.levels[i + 1 :])
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for i in range(0, len(self.levels) + 1)
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)
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class DayTwoSolver(Solver):
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reports: list[Report]
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@override
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def __init__(self, puzzle_input: str):
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self.reports = list(
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Report(tuple(int(level) for level in line.split(" ")))
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for line in puzzle_input.strip().splitlines()
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)
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@override
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def solve_p1(self) -> int:
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safe_reports = filter(Report.is_gradual_monotonic, self.reports)
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return ilen(safe_reports)
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@override
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def solve_p2(self) -> int:
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safe_reports = filter(
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lambda report: any(
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report_variation.is_gradual_monotonic()
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for report_variation in report.permute_dampened_variations()
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),
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self.reports,
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)
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return ilen(safe_reports)
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class TestDayNSolver(TestCase):
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def test(self):
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solver = DayTwoSolver(
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dedent(
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"""
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7 6 4 2 1
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1 2 7 8 9
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9 7 6 2 1
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1 3 2 4 5
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8 6 4 4 1
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1 3 6 7 9
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"""
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)
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)
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self.assertListEqual(
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solver.reports,
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[
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Report((7, 6, 4, 2, 1)),
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Report((1, 2, 7, 8, 9)),
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Report((9, 7, 6, 2, 1)),
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Report((1, 3, 2, 4, 5)),
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Report((8, 6, 4, 4, 1)),
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Report((1, 3, 6, 7, 9)),
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],
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)
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self.assertEqual(solver.solve_p1(), 2)
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self.assertEqual(solver.solve_p2(), 4)
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