1 files changed, 81 insertions, 0 deletions
diff --git a/2020/16/puzzle-2.py b/2020/16/puzzle-2.py
new file mode 100755
index 0000000..1060049
--- /dev/null
+++ b/2020/16/puzzle-2.py
@@ -0,0 +1,81 @@
+#!/usr/bin/env python3
+
+from functools import reduce
+from operator import mul
+
+
+def not_reduced(label_dict: dict[int, str]) -> bool:
+	for i in label_dict:
+		if len(label_dict[i]) != 1:
+			return True
+	return False
+
+
+def main() -> None:
+	with open("input", "r") as f:
+		data = f.readlines()
+
+	i = 0
+	valid: list[int] = []
+	labels: list[str] = []
+	while data[i] != "\n":
+		labels.append(data[i].split(":")[0])
+		ranges = data[i].split(": ")[1].split(" or ")
+		for _range in ranges:
+			bounds = tuple(map(int, _range.split("-")))
+			for j in range(bounds[0], bounds[1] + 1):
+				valid.append(j)
+		i += 1
+
+	# Skip to nearby tickets
+	i += 5
+
+	vtickets: list[tuple[int, ...]] = []
+	for j in range(i, len(data)):
+		fields = tuple(map(int, data[j].split(",")))
+		check = True
+		for field in fields:
+			if field not in valid:
+				check = False
+				break
+		if check == True:
+			vtickets.append(tuple(map(int, data[j].split(","))))
+
+	label_dict: dict[int, list[str]] = {}
+	for i in range(len(labels)):
+		label_dict[i] = []
+
+	# Triple for loop, gross!
+	for label in labels:
+		valid: list[list[int]] = []
+		ranges = data[labels.index(label)].split(": ")[1].split(" or ")
+		for _range in ranges:
+			bounds = tuple(map(int, _range.split("-")))
+			for i in range(bounds[0], bounds[1] + 1):
+				valid.append(i)
+
+		# For each column
+		for i in range(len(labels)):
+			allvalid = True
+			for ticket in vtickets:
+				if ticket[i] not in valid:
+					allvalid = False
+					break
+
+			if allvalid == True:
+				label_dict[i].append(label)
+
+	# Reduce the label dictionary
+	while not_reduced(label_dict):
+		for i in label_dict:
+			if len((l := label_dict[i])) == 1:
+				for j in label_dict:
+					if l[0] in label_dict[j] and i != j:
+						label_dict[j].remove(l[0])
+
+	my_ticket = tuple(map(int, data[data.index("your ticket:\n") + 1].split(",")))
+	print(reduce(mul, [x for x in my_ticket if "departure" in label_dict[my_ticket.index(x)][0]],))
+
+
+if __name__ == "__main__":
+	main()