40 lines
1.3 KiB
Python
40 lines
1.3 KiB
Python
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# SPDX-License-Identifier: MIT
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# Copyright (c) 2020 Akumatic
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#
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# https://adventofcode.com/2020/day/19
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import re
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def parse_rules(input: list) -> dict:
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return dict(rule.split(": ") for rule in input)
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def read_file() -> tuple:
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with open(f"{__file__.rstrip('code.py')}input.txt", "r") as f:
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blocks = [block.split("\n") for block in f.read().strip().split("\n\n")]
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return parse_rules(blocks[0]), blocks[1]
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def regex_pattern(word, rules):
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check = word.split()
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pattern = f" {word} "
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while check:
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value = check.pop(0)
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rule = rules[value]
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if '"' not in rule:
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check += set([w for w in rule.split() if w not in ("|", "(", ")+")])
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replacement = "( " + rule + " )" if "|" in rule else rule
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pattern = pattern.replace(f" {value} ", f" {replacement} ")
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return pattern.replace('"', "").replace(" ", "")
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def part1(rules, words):
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pattern = regex_pattern(rules['0'], rules)
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return sum([bool(re.fullmatch(pattern, word)) for word in words])
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def part2(rules, words):
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rules["8"] = "( 42 )+"
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rules["11"] = "|".join(" 42 "*i + " 31 "*i for i in range(1, 6))
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return part1(rules, words)
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if __name__ == "__main__":
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rules, words = read_file()
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print(f"Part 1: {part1(rules, words)}")
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print(f"Part 2: {part2(rules, words)}")
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