75 lines
2.2 KiB
Python
75 lines
2.2 KiB
Python
def load_input() -> list[str]:
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with open('../.input/day03', 'r') as f:
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return [line.strip() for line in f.readlines()]
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def solve1() -> int:
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input = load_input()
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cache = [{"0": 0, "1": 0} for _ in range(len(input[0]))]
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for binary in input:
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for i, c in enumerate(binary):
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cache[i][c] += 1
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gamma, epsilon = map(sum, zip(*[
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(2**i, 0) if c["1"] > c["0"] else (0, 2**i)
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for i, c in enumerate(reversed(cache))
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]))
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return gamma * epsilon
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def find_single(input: list[str], reverse: bool = False) -> int:
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cache = [{"0": 0, "1": 0} for _ in range(len(input[0]))]
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remaining = input[:]
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for binary in remaining:
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for i, digit in enumerate(binary):
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cache[i][digit] += 1
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for i, c in enumerate(cache):
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if len(remaining) == 1:
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break
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generator = (entry for entry in remaining)
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remaining = []
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winning_digit = ("0" if c["0"] <= c["1"] else "1") if reverse else ("1" if c["1"] >= c["0"] else "0")
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for binary in generator:
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if binary[i] == winning_digit:
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remaining.append(binary)
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else:
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for digit, cache_dict in zip(binary, cache):
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cache_dict[digit] -= 1
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return remaining[0]
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def solve2() -> int:
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input = load_input()
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oxygen, carbon = input[:], input[:]
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res_o = sum(2**int(i) for i, x in enumerate(reversed(find_single(oxygen, reverse=False))) if x == "1")
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res_c = sum(2**int(i) for i, x in enumerate(reversed(find_single(carbon, reverse=True))) if x == "1")
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return res_o * res_c
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import numpy as np
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def load_input_np() -> np.ndarray:
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with open('../.input/day03', 'r') as f:
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return np.array([list(map(np.int32, list(i.strip()))) for i in f.readlines()])
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def solve1_np() -> int:
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input = load_input_np()
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binary = (input.mean(axis=0) >= 0.5)
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invert = np.logical_not(binary)
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decimalize = 2 ** np.arange(binary.shape[0])[::-1]
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return sum(binary * decimalize) * sum(invert * decimalize)
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if __name__ == "__main__":
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print(solve1()) # 4001724
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print(solve2()) # 587895
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print(solve1_np()) # 4001724
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