blob: 58e8f4fe62d09811771bf751ecdef79d58d8283d (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
|
from utils import open_day
Bits = tuple[bool, ...]
Input = list[Bits]
def most_common(nums: list[Bits], n: int) -> bool:
count: int = 0
for num in nums: count += num[n]
return count >= len(nums) - count
def bits_to_int(bits: Bits) -> int:
return sum(b * 2 ** i for i, b in enumerate(reversed(bits)))
def part1(nums: Input) -> int:
gamma: Bits = tuple(most_common(nums, i) for i in range(len(nums[0])))
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(nums, bit) ^ complement
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_day(3)]
print(part1(inp))
print(part2(inp))
|
