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1 files changed, 59 insertions, 0 deletions

diff --git a/2020/19/puzzle-1.py b/2020/19/puzzle-1.py
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+++ b/2020/19/puzzle-1.py
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+#!/usr/bin/env python3
+
+from collections import OrderedDict
+
+
+def main() -> None:
+	with open("input", "r") as f:
+		data = f.readlines()
+
+	i = 0
+	rules: list[tuple[str]] = []
+	while data[i] != "\n":
+		rules.append(tuple(x for x in tuple(data[i].split(": "))))
+		i += 1
+
+	tests: list[str] = []
+	for line in data:
+		tests.append(line.strip())
+
+	patterns: dict[str, list[str]] = {}
+
+	# Get "a" and "b" out of the way to do less comparisons in the next loop. Also make use of
+	# this loop to strip newlines off of all the rules.
+	for rule in rules:
+		rules[rules.index(rule)] = (rule[0], rule[1].strip())
+		if len(rule[1]) == 4:
+			patterns[rule[0]] = [rule[1][1]]
+
+	while len(patterns) != len(rules):
+		for rule in rules:
+			if rule[0] in patterns:
+				continue
+
+			res = rule[1].split(" | ")
+			req_rules = list(OrderedDict.fromkeys(" ".join(res).split(" ")))
+			all_in = True
+			for req in req_rules:
+				if req not in patterns:
+					all_in = False
+					break
+			if all_in == True:
+				all_combos: list[str] = []
+				for re in res:
+					re = re.split(" ")
+					if len(re) == 1:
+						all_combos.extend(patterns[re[0]])
+					else:
+						for x in patterns[re[0]]:
+							for y in patterns[re[1]]:
+								all_combos.append(f"{x}{y}")
+						all_combos = list(OrderedDict.fromkeys(all_combos))
+
+				patterns[rule[0]] = all_combos
+
+	print(len([test for test in tests if test in patterns["0"]]))
+
+
+if __name__ == "__main__":
+	main()