first solution for day 4

04/04.py

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+def read_file():
+	with open("input.txt","r") as f:
+		# first, we split into separate passports.
+		raw_passports = f.read().split('\n\n')
+		# then, we split each passport into fields, by newline or space.
+		split_passports = []
+		for passport in raw_passports:
+			split_passports.append(passport.split())
+		# finally, we convert to a dictionary.
+		passports = []
+		for passport in split_passports:
+			passport_dict = {}
+			for field in passport:
+				key, value = field.split(':')
+				passport_dict[key] = value
+			passports.append(passport_dict)
+		# all passports should now be normalized to dicts.
+		return passports 
+
+def valid(passport):
+	required_fields = ['byr', 'iyr', 'eyr', 'hgt', 'hcl', 'ecl', 'pid']
+	for field in required_fields:
+		if field not in passport:
+			return False
+	return True
+
+def part1(passports):
+	valid_passports = 0
+	for passport in passports:
+		if valid(passport):
+			valid_passports += 1
+	return valid_passports
+
+def valid_data(passport):
+	# first, we need to check if all required fields are present.
+	if not valid(passport):
+		return False
+	# byr must be four digits 1920 - 2002
+	byr = int(passport['byr'])
+	if not (1920 <= byr <= 2002):
+		return False
+	# iyr must be four digits 2010 - 2020
+	iyr = int(passport['iyr'])
+	if not (2010 <= iyr <= 2020):
+		return False
+	#eyr must be four digits 2020 - 2030
+	eyr = int(passport['eyr'])
+	if not (2020 <= eyr <= 2030):
+		return False
+	# hgt must be 150-193cm or 59-76in
+	hgt = passport['hgt']
+	if hgt.endswith('cm'):
+		hgt = int(hgt[:-2])
+		if not (150 <= hgt <= 193):
+			return False
+	elif hgt.endswith('in'):
+		hgt = int(hgt[:-2])
+		if not (59 <= hgt <= 76):
+			return False
+	else:
+		return False
+	# hcl must be hexcode
+	hcl = passport['hcl']
+	import re
+	if not re.match(r'^#(?:[0-9a-fA-F]{1,2}){3}$', hcl):
+		return False
+	# ecl must be exactly one of: amb blu brn gry grn hzl oth.
+	valid_ecls = ['amb', 'blu', 'brn', 'gry', 'grn', 'hzl', 'oth']
+	ecl = passport['ecl']
+	if ecl not in valid_ecls:
+		return False
+	# pid must be 9 digits long
+	pid = passport['pid']
+	if len(pid) != 9:
+		return False
+	# cid is ignored
+	return True
+
+
+def part2(passports):
+	valid_passports = 0
+	for passport in passports:
+		if valid_data(passport):
+			valid_passports += 1
+	return valid_passports
+		
+def main():
+	passports = read_file()
+	print(f'{part1(passports)=}')
+	print(f'{part2(passports)=}')
+
+
+if __name__ == "__main__":
+	main()