171 lines
5.7 KiB
Plaintext
171 lines
5.7 KiB
Plaintext
# Advent of Code
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--- Day 4: Passport Processing ---
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You arrive at the airport only to realize that you grabbed your North Pole Credentials
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instead of your passport. While these documents are extremely similar, North Pole
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Credentials aren't issued by a country and therefore aren't actually valid documentation
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for travel in most of the world.
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It seems like you're not the only one having problems, though; a very long line has formed
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for the automatic passport scanners, and the delay could upset your travel itinerary.
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Due to some questionable network security, you realize you might be able to solve both of
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these problems at the same time.
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The automatic passport scanners are slow because they're having trouble detecting which
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passports have all required fields. The expected fields are as follows:
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• byr (Birth Year)
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• iyr (Issue Year)
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• eyr (Expiration Year)
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• hgt (Height)
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• hcl (Hair Color)
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• ecl (Eye Color)
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• pid (Passport ID)
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• cid (Country ID)
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Passport data is validated in batch files (your puzzle input). Each passport is represented
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as a sequence of key:value pairs separated by spaces or newlines. Passports are separated
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by blank lines.
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Here is an example batch file containing four passports:
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ecl:gry pid:860033327 eyr:2020 hcl:#fffffd
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byr:1937 iyr:2017 cid:147 hgt:183cm
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iyr:2013 ecl:amb cid:350 eyr:2023 pid:028048884
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hcl:#cfa07d byr:1929
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hcl:#ae17e1 iyr:2013
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eyr:2024
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ecl:brn pid:760753108 byr:1931
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hgt:179cm
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hcl:#cfa07d eyr:2025 pid:166559648
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iyr:2011 ecl:brn hgt:59in
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The first passport is valid - all eight fields are present. The second passport is invalid
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- it is missing hgt (the Height field).
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The third passport is interesting; the only missing field is cid, so it looks like data
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from North Pole Credentials, not a passport at all! Surely, nobody would mind if you made
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the system temporarily ignore missing cid fields. Treat this "passport" as valid.
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The fourth passport is missing two fields, cid and byr. Missing cid is fine, but missing
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any other field is not, so this passport is invalid.
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According to the above rules, your improved system would report 2 valid passports.
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Count the number of valid passports - those that have all required fields. Treat cid as
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optional. In your batch file, how many passports are valid?
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Your puzzle answer was 256.
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--- Part Two ---
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The line is moving more quickly now, but you overhear airport security talking about how
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passports with invalid data are getting through. Better add some data validation, quick!
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You can continue to ignore the cid field, but each other field has strict rules about what
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values are valid for automatic validation:
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• byr (Birth Year) - four digits; at least 1920 and at most 2002.
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• iyr (Issue Year) - four digits; at least 2010 and at most 2020.
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• eyr (Expiration Year) - four digits; at least 2020 and at most 2030.
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• hgt (Height) - a number followed by either cm or in:
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• If cm, the number must be at least 150 and at most 193.
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• If in, the number must be at least 59 and at most 76.
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• hcl (Hair Color) - a # followed by exactly six characters 0-9 or a-f.
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• ecl (Eye Color) - exactly one of: amb blu brn gry grn hzl oth.
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• pid (Passport ID) - a nine-digit number, including leading zeroes.
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• cid (Country ID) - ignored, missing or not.
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Your job is to count the passports where all required fields are both present and valid
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according to the above rules. Here are some example values:
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byr valid: 2002
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byr invalid: 2003
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hgt valid: 60in
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hgt valid: 190cm
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hgt invalid: 190in
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hgt invalid: 190
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hcl valid: #123abc
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hcl invalid: #123abz
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hcl invalid: 123abc
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ecl valid: brn
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ecl invalid: wat
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pid valid: 000000001
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pid invalid: 0123456789
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Here are some invalid passports:
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eyr:1972 cid:100
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hcl:#18171d ecl:amb hgt:170 pid:186cm iyr:2018 byr:1926
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iyr:2019
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hcl:#602927 eyr:1967 hgt:170cm
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ecl:grn pid:012533040 byr:1946
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hcl:dab227 iyr:2012
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ecl:brn hgt:182cm pid:021572410 eyr:2020 byr:1992 cid:277
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hgt:59cm ecl:zzz
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eyr:2038 hcl:74454a iyr:2023
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pid:3556412378 byr:2007
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Here are some valid passports:
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pid:087499704 hgt:74in ecl:grn iyr:2012 eyr:2030 byr:1980
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hcl:#623a2f
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eyr:2029 ecl:blu cid:129 byr:1989
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iyr:2014 pid:896056539 hcl:#a97842 hgt:165cm
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hcl:#888785
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hgt:164cm byr:2001 iyr:2015 cid:88
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pid:545766238 ecl:hzl
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eyr:2022
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iyr:2010 hgt:158cm hcl:#b6652a ecl:blu byr:1944 eyr:2021 pid:093154719
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Count the number of valid passports - those that have all required fields and valid values.
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Continue to treat cid as optional. In your batch file, how many passports are valid?
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Your puzzle answer was 198.
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Both parts of this puzzle are complete! They provide two gold stars: **
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At this point, you should return to your Advent calendar and try another puzzle.
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If you still want to see it, you can get your puzzle input.
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You can also [Shareon Twitter Mastodon] this puzzle.
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References
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Visible links
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. https://adventofcode.com/
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. https://adventofcode.com/2020/about
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. https://adventofcode.com/2020/events
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. https://adventofcode.com/2020/settings
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. https://adventofcode.com/2020/auth/logout
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. Advent of Code Supporter
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https://adventofcode.com/2020/support
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. https://adventofcode.com/2020
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. https://adventofcode.com/2020
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. https://adventofcode.com/2020/support
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. https://adventofcode.com/2020/sponsors
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. https://adventofcode.com/2020/leaderboard
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. https://adventofcode.com/2020/stats
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. https://adventofcode.com/2020/sponsors
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. https://github.com/
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. https://adventofcode.com/2020
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. https://adventofcode.com/2020/day/4/input
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