85 lines
2.0 KiB
Python
85 lines
2.0 KiB
Python
from functools import partial
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from typing import Callable, Iterator, NamedTuple
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from math import log
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test_input = """
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190: 10 19
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3267: 81 40 27
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83: 17 5
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156: 15 6
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7290: 6 8 6 15
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161011: 16 10 13
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192: 17 8 14
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21037: 9 7 18 13
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292: 11 6 16 20
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""".strip()
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test_solution_p1 = 3749
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test_solution_p2 = 11387
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def solve_p1(puzzle_input: str) -> int:
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equations = _parse_equations(puzzle_input)
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calibration_guard = partial(
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_is_calibrated,
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[
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int.__add__,
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int.__mul__,
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],
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)
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return sum(equation.target for equation in filter(calibration_guard, equations))
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def solve_p2(puzzle_input: str) -> int:
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equations = _parse_equations(puzzle_input)
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calibration_guard = partial(
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_is_calibrated,
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[
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int.__add__,
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int.__mul__,
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_concat_ints,
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],
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)
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return sum(equation.target for equation in filter(calibration_guard, equations))
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class Equation(NamedTuple):
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target: int
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factors: tuple[int, ...]
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def _parse_equations(puzzle_input: str) -> Iterator[Equation]:
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for line in puzzle_input.split("\n"):
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if line:
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result_string, _, factors_string = line.partition(": ")
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yield Equation(
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int(result_string),
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tuple(map(int, factors_string.split(" "))),
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)
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Operator = Callable[[int, int], int]
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def _is_calibrated(operators: list[Operator], equation: Equation) -> bool:
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def _eval_permutations(factors: tuple[int, ...]) -> Iterator[int]:
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assert len(factors) > 0
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tail = factors[-1]
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if len(factors) == 1:
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yield tail
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return
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for head in _eval_permutations(factors[:-1]):
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if head > equation.target:
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continue
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for operator in operators:
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yield operator(head, tail)
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return any(
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result == equation.target for result in _eval_permutations(equation.factors)
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)
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def _concat_ints(a: int, b: int) -> int:
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return 10 ** int(log(b, 10) + 1) * a + b
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