56 lines
1.5 KiB
Python
56 lines
1.5 KiB
Python
from functools import cache
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from math import log
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from typing import override
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from unittest import TestCase
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from puzzles._solver import Solver
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class DayElevenSolver(Solver):
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stones: tuple[int, ...]
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@override
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def __init__(self, puzzle_input: str):
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self.stones = tuple(map(int, puzzle_input.strip().split(" ")))
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@override
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def solve_p1(self) -> int:
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return sum(sum_descendants(stone, 25) for stone in self.stones)
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@override
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def solve_p2(self) -> int:
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return sum(sum_descendants(stone, 75) for stone in self.stones)
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@cache
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def sum_descendants(stone: int, blinks: int) -> int:
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if blinks == 0:
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return 1
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if stone == 0:
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return sum_descendants(1, blinks - 1)
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digit_len = int(log(stone, 10)) + 1
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if digit_len % 2 == 0:
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left_digits, right_digits = divmod(stone, 10 ** (digit_len // 2))
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return sum_descendants(left_digits, blinks - 1) + sum_descendants(
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right_digits, blinks - 1
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)
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return sum_descendants(stone * 2024, blinks - 1)
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class TestDayElevenSolver(TestCase):
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def test_sum_descendants(self):
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self.assertEqual(sum_descendants(0, 1), 1)
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self.assertEqual(sum_descendants(17, 1), 2)
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self.assertEqual(sum_descendants(125, 4), 3)
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def test_parse(self):
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solver = DayElevenSolver("123 4 56\n")
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self.assertEqual(solver.stones, (123, 4, 56))
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def test_solve_p1(self):
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solver = DayElevenSolver("125 17\n")
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self.assertEqual(solver.solve_p1(), 55312)
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