71 lines
2.0 KiB
Python
71 lines
2.0 KiB
Python
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from itertools import zip_longest
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def grouper(n, iterable):
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"grouper(3, 'ABCDEFG', 'x') --> ABC DEF Gxx"
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args = [iter(iterable)] * n
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return zip_longest(*args)
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def part1(sections):
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# consume seed section
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_, seeds = next(sections)
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seeds = [int(s) for s in seeds]
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for _, mapping in sections:
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seeds = [apply_mapping(s, mapping) for s in seeds]
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print(f"Part 1, lowest location number = {min(seeds)}")
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def part2(sections):
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# consume seed section
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_, seeds = next(sections)
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seeds = [int(s) for s in seeds]
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min_seed = 2**128
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for start_seed, length in grouper(2, seeds):
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subseeds = range(start_seed, start_seed + length)
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print(f"calculate_for_subseeds(subseeds len={len(subseeds)})")
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res = calculate_for_subseeds(subseeds, sections)
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mini = min(res)
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if mini < min_seed:
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min_seed = mini
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print(f"Part 2 {min_seed}")
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def calculate_for_subseeds(seeds, sections):
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new_seeds = seeds
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for _, mapping in sections:
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new_seeds = [apply_mapping(s, mapping) for s in new_seeds]
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return new_seeds
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def apply_mapping(seed, mapping):
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for dst, src, length in grouper(3, mapping):
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src, length, dst = int(src), int(length), int(dst)
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end = src + length
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if src <= seed < end:
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return seed + (dst-src)
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return seed
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def parse_input(infile):
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with open(infile) as f:
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sections = f.read().split("\n\n")
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sections = ((title, numbers) for title, numbers in (s.split(":") for s in sections))
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sections = ((title, numbers.split()) for title, numbers in sections)
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return sections
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if __name__ == "__main__":
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import sys
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import os
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SCRIPTPATH = os.path.dirname(os.path.realpath(__file__))
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infile = next(iter(sys.argv[1:]), None)
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sections = parse_input(infile or os.path.join(SCRIPTPATH, "example.txt"))
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part1(sections)
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sections = parse_input(infile or os.path.join(SCRIPTPATH, "example.txt"))
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part2(sections)
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