46 lines
1.3 KiB
Python
46 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/10
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def read_file(filename: str = "input.txt") -> list:
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with open(f"{__file__.rstrip('code.py')}{filename}", "r") as f:
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return [line for line in f.read().strip().split("\n")]
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def shorten(s: str) -> str:
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changes = True
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while changes:
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tmp = s.replace("()", "").replace("[]", "").replace("{}", "").replace("<>", "")
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changes = (tmp != s)
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s = tmp
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return s
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def score_illegal(s: str) -> str:
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points = {")": 3, "]": 57, "}": 1197, ">": 25137}
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return points[[x for x in shorten(s) if x in (")", "]", "}", ">")][0]]
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def score_incomplete(s: str) -> str:
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points = {"(": 1, "[": 2, "{": 3, "<": 4}
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score = 0
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for c in shorten(s)[::-1]:
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score *= 5
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score += points[c]
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return score
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def validate(line: str) -> bool:
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short = shorten(line)
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return sum(short.count(c) for c in (")", "]", "}", ">")) == 0
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def part1(vals: list) -> int:
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return sum(score_illegal(line) for line in vals if not validate(line))
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def part2(vals: list) -> int:
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scores = [score_incomplete(line) for line in vals if validate(line)]
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scores.sort()
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return scores[len(scores) // 2]
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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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