92 lines
3.1 KiB
Python
92 lines
3.1 KiB
Python
import re
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from itertools import combinations
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from math import ceil
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from tools.aoc import AOCDay
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from typing import Any
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re_pair = re.compile(r"\[(\d+),(\d+)\]")
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re_lnum = re.compile(r".*[^\d](\d+)")
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re_rnum = re.compile(r"(\d+)")
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re_bignum = re.compile(r"(\d\d+)")
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class Snailfish:
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def __init__(self, fish_str: str):
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self.pairs = fish_str
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while self.reduce():
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pass
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def __add__(self, other: 'Snailfish'):
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return Snailfish("[%s,%s]" % (self.pairs, other.pairs))
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def reduce(self):
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open_count = 0
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for i, c in enumerate(self.pairs):
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if c == "]":
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open_count -= 1
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elif c == "[":
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open_count += 1
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if open_count == 5:
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explode_pair_match = re_pair.search(self.pairs, i)
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index_l, index_r = explode_pair_match.span()
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explode_left, explode_right = map(int, explode_pair_match.groups())
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lnum_old = rnum_old = lnum_new = rnum_new = ""
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lnum_index = index_l
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rnum_index = index_r
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if left_num := re_lnum.search(self.pairs[:index_l]):
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lnum_old = left_num.groups()[0]
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lnum_new = str(int(lnum_old) + explode_left)
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lnum_index = left_num.span()[1] - len(lnum_old)
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if right_num := re_rnum.search(self.pairs, index_r):
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rnum_old = right_num.groups()[0]
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rnum_new = str(int(rnum_old) + explode_right)
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rnum_index = right_num.span()[0]
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self.pairs = "".join([
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self.pairs[:lnum_index],
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lnum_new,
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self.pairs[lnum_index + len(lnum_old):index_l],
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"0",
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self.pairs[index_r:rnum_index],
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rnum_new,
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self.pairs[rnum_index + len(rnum_old):]
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])
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return True
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if big_num_match := re_bignum.search(self.pairs):
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num = int(big_num_match.group())
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self.pairs = self.pairs.replace(big_num_match.group(), "[%d,%d]" % (num // 2, int(ceil(num / 2))), 1)
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return True
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return False
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def getMagnitude(self) -> int:
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pairs = self.pairs
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while match := re_pair.findall(pairs):
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for num1, num2 in match:
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pairs = pairs.replace("[%s,%s]" % (num1, num2), str(int(num1) * 3 + int(num2) * 2))
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return int(pairs)
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class Day(AOCDay):
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test_solutions_p1 = [4140, 4417]
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test_solutions_p2 = [3993, 4796]
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def part1(self) -> Any:
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snailfishes = [Snailfish(x) for x in self.getInput()]
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return sum(snailfishes[1:], start=snailfishes[0]).getMagnitude()
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def part2(self) -> Any:
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snailfishes = [Snailfish(x) for x in self.getInput()]
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max_mag = 0
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for a, b in combinations(snailfishes, 2):
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sub_mag_a = (a + b).getMagnitude()
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sub_mag_b = (b + a).getMagnitude()
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max_mag = max(max_mag, sub_mag_a, sub_mag_b)
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return max_mag
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