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from typing import Generator
from collections.abc import Iterable
Bits = tuple[bool, ...]
Input = list[Bits]
def column(rows: Iterable[Bits], n: int) -> Generator[bool, None, None]:
for row in rows:
yield row[n]
def most_common(bits: Iterable[bool]) -> bool:
count1: int = 0
length: int = 0
for b in bits:
if b: count1 += 1
length += 1
return count1 >= length - count1
def bits_to_int(bits: Bits) -> int:
return sum(b * 2 ** i for i, b in enumerate(reversed(bits)))
def part1(nums: Input) -> int:
nbits: int = len(nums[0])
gamma: Bits = tuple(most_common(column(inp, i)) for i in range(nbits))
epsilon: Bits = tuple(not bit for bit in gamma)
return bits_to_int(gamma) * bits_to_int(epsilon)
def part2_impl(nums: Input, complement: bool, bit: int = 0) -> Bits:
if len(nums) == 1:
return nums[0]
target: bool = most_common(column(nums, bit))
if complement:
target = not target
nums = list(filter(lambda n: n[bit] == target, nums))
return part2_impl(nums, complement, bit + 1)
def part2(nums: Input) -> int:
oxygen: Bits = part2_impl(nums, False)
co2: Bits = part2_impl(nums, True)
return bits_to_int(oxygen) * bits_to_int(co2)
inp: Input = [tuple(c == '1' for c in l.strip()) for l in open('3.in')]
print(part1(inp))
print(part2(inp))
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