def main():
# open the file, split into blocks: <fields>, <your ticket>, <other tickets>
with open(f"{getcwd()}/2020/day16/input.txt") as file:
file = file.read().strip().split("\n\n")
allFields = re.findall(r"(.*): (\d+-\d+) or (\d+-\d+)", file[0])
yourTicket = file[1].splitlines()[1]
otherTickets = file[2].splitlines()[1:]
validTicket = Ticket()
# fill the ticket with all the fields and ranges in the input
for field in allFields:
validTicket.addFieldRange(field[0], [field[1], field[2]])
# list of all valid tickets (just tuples of values that appear on the ticket)
validTickets = [
tuple(strToIntSequence(line)) for line in map(str.strip, otherTickets)
if isValidTicket(strToIntSequence(line), validTicket)
]
# a list of sets of the possible labels for each field
fieldList = [
validTicket.getFields().copy() for _ in range(len(validTickets[0]))
]
# find the arrangement of labels for the tickets
for i, fieldSet in enumerate(fieldList):
fieldsToRemove = set()
for field in fieldSet:
for ticket in validTickets:
if not validTicket.isValidForField(field, ticket[i]):
fieldsToRemove.add(field)
break
fieldSet -= fieldsToRemove
if len(fieldSet) == 1:
removeUnique(i, list(fieldSet)[0], fieldList)
fieldList = [list(item)[0] for item in fieldList]
# calculate ticket score
score = 1
for label, value in zip(fieldList, strToIntSequence(yourTicket)):
if label.startswith("departure"):
score *= value
print(f"Product of departure fields: {score}")
