37 lines
1.3 KiB
Python
37 lines
1.3 KiB
Python
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# SPDX-License-Identifier: MIT
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# Copyright (c) 2021 Akumatic
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#
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# https://adventofcode.com/2021/day/03
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def read_file() -> list:
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with open(f"{__file__.rstrip('code.py')}input.txt", "r") as f:
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return [line for line in f.read().strip().split("\n")]
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def get_mcb(vals: list) -> list:
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bit_count = [sum(int(num[i]) for num in vals) for i in range(len(vals[0]))]
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return [1 if cnt >= (len(vals) - cnt) else 0 for cnt in bit_count]
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def reduce_reports(reports: list, invert: bool = False) -> int:
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for i in range(0, len(reports[0])):
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mcb = get_mcb(reports)[i]
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bit = str(mcb if not invert else 1 - mcb)
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reports = [rep for rep in reports if rep[i] == bit]
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if len(reports) == 1:
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break
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return int(reports[0], 2)
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def part1(vals: list) -> int:
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mcb = get_mcb(vals)
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gamma = "".join(["1" if bit else "0" for bit in mcb])
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epsilon = "".join(["0" if bit else "1" for bit in mcb])
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return int(gamma, 2) * int(epsilon, 2)
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def part2(vals: list) -> int:
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ogr = reduce_reports(vals[:]) # oxygen generator rating
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csr = reduce_reports(vals[:], invert=True) # CO2 scrubber rating
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return ogr * csr
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if __name__ == "__main__":
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vals = read_file()
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print(f"Part 1: {part1(vals)}")
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print(f"Part 2: {part2(vals)}")
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