diff --git a/2020/d19/ex1/ex1.py b/2020/d19/ex1/ex1.py new file mode 100755 index 0000000..2741dfd --- /dev/null +++ b/2020/d19/ex1/ex1.py @@ -0,0 +1,48 @@ +#!/usr/bin/env python + +import itertools +import re +import sys +from typing import Dict, List + + +def parse_rule(raw_rules: List[str]) -> str: + parsed: Dict[int, str] = {} + rules = {int(num): rule.strip() for num, rule in (i.split(":") for i in raw_rules)} + + for n, r in rules.items(): + if '"' not in r: + continue + parsed[n] = r.replace('"', "") + + while 0 not in parsed: + for num in parsed: + if num not in rules: + continue + rules.pop(num) + + for num, r in rules.items(): + nums = list(reversed(sorted(map(int, re.findall("(\\d+)", r))))) + if all(n in parsed for n in nums): + for n in nums: + r = re.sub(str(n), parsed[n], r) # Bigger numbers replaced first + r = r.replace(" ", "") + parsed[num] = "(" + r + ")" + return parsed[0] + + +def solve(raw: List[str]) -> int: + pattern = re.compile(parse_rule(list(itertools.takewhile(len, raw)))) + + return sum( + pattern.fullmatch(line) is not None for line in itertools.dropwhile(len, raw) + ) + + +def main() -> None: + input = [line.strip() for line in sys.stdin.readlines()] + print(solve(input)) + + +if __name__ == "__main__": + main()