From: Neil Smith <neil.git@njae.me.uk>
Date: Wed, 9 Dec 2020 15:34:22 +0000 (+0000)
Subject: Done day 4
X-Git-Url: https://git.njae.me.uk/?p=advent-of-code-20.git;a=commitdiff_plain;h=1949f629afb7c8d0672207bc9599c74dc19f9848

Done day 4
---

diff --git a/advent04/package.yaml b/advent04/package.yaml
new file mode 100644
index 0000000..60d0bca
--- /dev/null
+++ b/advent04/package.yaml
@@ -0,0 +1,61 @@
+# This YAML file describes your package. Stack will automatically generate a
+# Cabal file when you run `stack build`. See the hpack website for help with
+# this file: <https://github.com/sol/hpack>.
+
+name: advent04
+synopsis: Advent of Code
+version: '0.0.1'
+
+default-extensions:
+- AllowAmbiguousTypes
+- ApplicativeDo
+- BangPatterns
+- BlockArguments
+- DataKinds
+- DeriveFoldable
+- DeriveFunctor
+- DeriveGeneric
+- DeriveTraversable
+- EmptyCase
+- FlexibleContexts
+- FlexibleInstances
+- FunctionalDependencies
+- GADTs
+- GeneralizedNewtypeDeriving
+- ImplicitParams
+- KindSignatures
+- LambdaCase
+- MonadComprehensions
+- MonoLocalBinds
+- MultiParamTypeClasses
+- MultiWayIf
+- NamedFieldPuns
+- NegativeLiterals
+- NumDecimals
+# - OverloadedLists
+- OverloadedStrings
+- PartialTypeSignatures
+- PatternGuards
+- PatternSynonyms
+- PolyKinds
+- RankNTypes
+- RecordWildCards
+- ScopedTypeVariables
+- TemplateHaskell
+- TransformListComp
+- TupleSections
+- TypeApplications
+- TypeFamilies
+- TypeInType
+- TypeOperators
+- ViewPatterns
+
+executables:
+  advent04:
+    main: advent04.hs
+    source-dirs: src
+    dependencies:
+    - base >= 2 && < 6
+    - text
+    - megaparsec
+    - containers
\ No newline at end of file
diff --git a/advent04/src/advent04.hs b/advent04/src/advent04.hs
new file mode 100644
index 0000000..1960f86
--- /dev/null
+++ b/advent04/src/advent04.hs
@@ -0,0 +1,134 @@
+-- import Debug.Trace
+
+import Data.Text (Text)
+import qualified Data.Text as T
+import qualified Data.Text.IO as TIO
+
+import Data.Void (Void)
+
+import Text.Megaparsec hiding (State)
+import Text.Megaparsec.Char
+import qualified Text.Megaparsec.Char.Lexer as L
+import qualified Control.Applicative as CA
+
+import qualified Data.Map.Strict as M
+import qualified Data.Set as S
+import Data.Char
+import Data.List
+
+-- import Text.Megaparsec.Debug
+
+type Passport = M.Map String String
+
+requiredFields = S.fromList ["byr", "iyr", "eyr", "hgt", "hcl", 
+    "ecl", "pid"]
+expectedFields = S.union requiredFields $ S.singleton "cid"
+
+
+main :: IO ()
+main = 
+  do  text <- TIO.readFile "data/advent04.txt"
+      let passports = successfulParse text
+      -- print $ length passports
+      putStrLn $ runTests
+      print $ part1 passports
+      print $ part2 passports
+
+part1 = length . filter hasRequiredFields 
+part2 = length . filter validPassport
+
+hasRequiredFields passport = S.null $ requiredFields `S.difference` (M.keysSet passport)
+
+validPassport :: Passport -> Bool
+validPassport passport = (hasRequiredFields passport) && (all validField $ M.assocs passport)
+
+validField :: (String, String) -> Bool
+validField (key, value) =
+  case key of
+    "byr" -> validRanged 1920 2002 value
+    "iyr" -> validRanged 2010 2020 value
+    "eyr" -> validRanged 2020 2030 value
+    "hgt" -> validHeight value
+    "hcl" -> validHex value
+    "ecl" -> validEye value
+    "pid" -> validPid value
+    "cid" -> True
+    _ -> False
+
+validRanged lower upper value = 
+  if all isDigit value
+  then v >= lower && v <= upper
+  else False
+  where v = read @Int value 
+
+validHeight value = 
+  if "cm" `isSuffixOf` value
+  then validRanged 150 193 v
+  else if "in" `isSuffixOf` value
+       then validRanged 59 76 v
+       else False
+  where v = reverse $ drop 2 $ reverse value
+
+validHex value = (length value == 7) && (head value == '#') && (all isHexDigit $ tail value)
+
+validEye value = value `S.member` eyeColours
+eyeColours = S.fromList ["amb", "blu", "brn", "gry", "grn", "hzl", "oth"]
+
+validPid value = (length value == 9) && (all isDigit value)
+
+runTests :: String -- [(Text, Bool)]
+runTests = if null failures
+           then "All tests passed"
+           else show failures
+  where failures = filter failedTest testCases
+
+failedTest :: (Text, Bool) -> Bool
+failedTest (passportText, expected) = actual /= expected
+  where passport = parseTestCase passportText
+        actual = validPassport passport
+
+parseTestCase :: Text -> Passport
+parseTestCase input = 
+  case parse passportP "test" input of
+    Left  _err -> M.empty
+    Right p -> p
+
+testCases = 
+  [ ("eyr:1972 cid:100 hcl:#18171d ecl:amb hgt:170 pid:186cm iyr:2018 byr:1926", False)
+  , ("iyr:2019\nhcl:#602927 eyr:1967 hgt:170cm\necl:grn pid:012533040 byr:1946", False)
+  , ("hcl:dab227 iyr:2012\necl:brn hgt:182cm pid:021572410 eyr:2020 byr:1992 cid:277", False)
+  , ("hgt:59cm ecl:zzz\neyr:2038 hcl:74454a iyr:2023\npid:3556412378 byr:2007", False)
+  , ("pid:087499704 hgt:74in ecl:grn iyr:2012 eyr:2030 byr:1980\nhcl:#623a2f", True)
+  , ("eyr:2029 ecl:blu cid:129 byr:1989\niyr:2014 pid:896056539 hcl:#a97842 hgt:165cm", True)
+  , ("hcl:#888785\nhgt:164cm byr:2001 iyr:2015 cid:88\npid:545766238 ecl:hzl\neyr:2022", True)
+  , ("iyr:2010 hgt:158cm hcl:#b6652a ecl:blu byr:1944 eyr:2021 pid:093154719", True)
+  ]
+
+
+-- Parse the input file
+type Parser = Parsec Void Text
+
+sc :: Parser ()
+sc = L.space (skipSome (    char ' ' 
+                       <|> char '\t' 
+                       <|> (try (newline <* notFollowedBy newline))
+                       )
+             ) CA.empty CA.empty
+
+blankLines = skipSome newline
+
+symb = L.symbol sc
+colonP = symb ":"
+hashChar = char '#'
+stringP = some (alphaNumChar <|> hashChar) <* sc
+
+kvP = (,) <$> stringP <* colonP <*> stringP
+
+passportsP = passportP `sepBy` blankLines
+passportP = M.fromList <$> many kvP
+
+successfulParse :: Text -> [Passport]
+successfulParse input = 
+  case parse passportsP "input" input of
+    Left  _err -> [] -- TIO.putStr $ T.pack $ parseErrorPretty err
+    Right passports -> passports
diff --git a/data/advent04.txt b/data/advent04.txt
new file mode 100644
index 0000000..646dcfe
--- /dev/null
+++ b/data/advent04.txt
@@ -0,0 +1,1169 @@
+byr:2024 iyr:2016
+eyr:2034 ecl:zzz pid:985592671 hcl:033b48
+hgt:181 cid:166
+
+hgt:66cm
+pid:152cm
+hcl:cfb18a eyr:1947
+byr:2020 ecl:zzz iyr:2029
+
+ecl:gry hcl:#888785 eyr:2023 cid:63
+iyr:2019 hgt:177cm
+pid:656793259
+
+pid:#5e832a
+ecl:dne hcl:#7d3b0c byr:2018 eyr:1928 hgt:61cm iyr:1936 cid:241
+
+hcl:#888785 ecl:oth eyr:2025
+pid:597580472
+iyr:2017 hgt:187cm byr:1957 cid:247
+
+eyr:2029 cid:145 iyr:2026 pid:178cm hgt:162in ecl:gry
+hcl:#a5d09f byr:2002
+
+eyr:2024
+ecl:amb
+pid:349191561 iyr:2018 hgt:156cm byr:1972
+hcl:#341e13
+
+byr:1998 pid:408617933
+hcl:#fffffd hgt:193cm eyr:2021 ecl:brn iyr:2013
+
+eyr:1964 byr:2026
+hcl:#cfa07d hgt:154cm pid:175cm cid:85 iyr:2018 ecl:gmt
+
+hgt:161cm
+pid:021086946
+iyr:2020 ecl:blu eyr:2024
+byr:1921
+
+pid:173cm cid:235 eyr:1935 iyr:1952 ecl:utc byr:2015 hgt:187
+hcl:6239ed
+
+iyr:2015 hcl:#18171d pid:2691566700 ecl:gmt hgt:68cm eyr:2032 byr:2016
+cid:341
+
+hcl:#c0946f
+iyr:2010 pid:941290886 eyr:2023 ecl:brn
+hgt:190cm
+byr:1927
+
+pid:423210256 eyr:2026 iyr:2011 byr:1926 hcl:#efcc98
+ecl:grn
+hgt:185cm cid:135
+
+ecl:blu eyr:2030
+byr:1996 hgt:154cm iyr:2019 pid:809421142
+hcl:#b6652a
+cid:250
+
+hcl:39615c iyr:1934 byr:2009 pid:7752456272 hgt:191cm
+eyr:2024 ecl:#5b7a58
+
+iyr:1938 hgt:160in hcl:#623a2f eyr:2031
+ecl:grn pid:169cm byr:1964
+
+ecl:grt byr:2004 hcl:026249 hgt:176in iyr:1933 eyr:2023
+pid:176cm
+
+hgt:167cm
+pid:023312072 ecl:oth iyr:2018 hcl:#866857 eyr:2024 byr:1994
+
+hcl:#c0946f
+ecl:blu iyr:2016
+eyr:2023 hgt:193cm
+pid:190756361 byr:1943
+cid:306
+
+iyr:2013 hgt:179cm ecl:oth
+cid:290 eyr:2020 pid:953948851
+hcl:#6b5442
+byr:1973
+
+pid:795414848
+cid:51
+ecl:oth iyr:2020 hcl:#ceb3a1 eyr:2026 byr:1995 hgt:186cm
+
+iyr:2020
+byr:1993 hgt:159cm pid:905121332
+ecl:brn eyr:2023
+hcl:#341e13
+
+ecl:hzl iyr:2017 eyr:2020 hcl:z byr:2003 hgt:163
+
+eyr:2038
+cid:342 hgt:116 iyr:2019 hcl:73db63 byr:1973 ecl:gry pid:468207739
+
+pid:022772899 eyr:2040 hgt:181cm
+ecl:dne
+hcl:#866857
+byr:1931 iyr:2012
+
+pid:36127238 eyr:2038 cid:227 iyr:1985 hgt:103 byr:2004
+hcl:z ecl:#45a680
+
+hgt:183cm
+iyr:2013 byr:1933 cid:112
+eyr:2024 pid:795616425
+hcl:#7d3b0c
+ecl:gry
+
+cid:236 byr:1985 hgt:160cm
+hcl:#6b5442 eyr:2028
+ecl:gmt pid:277781460 iyr:2018
+
+ecl:amb
+byr:1948 pid:750948701 eyr:2025 iyr:2013 hgt:62in hcl:#7d3b0c
+
+eyr:2029 iyr:2020 pid:385941629 byr:1998 hgt:153cm cid:321
+hcl:#623a2f
+
+byr:1966 hgt:69in iyr:2012
+pid:423254216
+eyr:2020 hcl:#602927 ecl:blu
+
+byr:2004 pid:14257358 cid:338 iyr:2010
+ecl:gry
+hcl:#602927
+hgt:152cm
+
+ecl:gry eyr:2027 hcl:#341e13
+iyr:2018 pid:298762877 hgt:162cm byr:1968
+
+hcl:#ceb3a1
+iyr:2019 ecl:brn eyr:2020 pid:575413143 byr:2030 hgt:185cm
+cid:159
+
+eyr:2025 pid:628251539 ecl:blu byr:1953 hgt:63in hcl:#18171d iyr:2016
+
+pid:973247326 byr:1925 hcl:#341e13 ecl:grn eyr:2028 hgt:156cm
+iyr:2014
+
+byr:1957 hgt:154cm
+hcl:#7d3b0c
+pid:062760305 eyr:2023 ecl:brn
+iyr:2012
+
+ecl:brn eyr:2029
+cid:250
+pid:477431667 hgt:177cm
+byr:1993 iyr:2020 hcl:#ceb3a1
+
+pid:155471269 iyr:2010 byr:1985 hgt:169cm eyr:2026 hcl:#694b7d cid:337 ecl:gry
+
+ecl:grt hgt:152in byr:2012
+pid:#b9d022 iyr:2030
+eyr:2037 hcl:z cid:201
+
+hcl:9270b3 eyr:2028
+hgt:71cm iyr:2017 pid:#6c7af7 ecl:grn byr:1971
+
+pid:#0ab7e1 hgt:166cm byr:1929
+cid:289
+hcl:#623a2f iyr:2005
+ecl:amb
+
+pid:967754435
+hgt:175cm hcl:#341e13 ecl:utc iyr:2023 eyr:1949 byr:1988
+
+byr:1942 ecl:brn eyr:2023 pid:898126666 hgt:182cm cid:138
+hcl:#866857
+iyr:2010
+
+eyr:2027 iyr:2019 byr:1953 pid:760664328 hcl:#b6652a
+ecl:grn hgt:155cm
+
+iyr:2018
+ecl:brn hcl:#18171d pid:953129359 hgt:167cm eyr:2030 byr:1974
+
+cid:77
+pid:975070417 hcl:#b6652a ecl:amb iyr:2013 byr:1995
+eyr:2025 hgt:184cm
+
+hgt:168cm
+eyr:2026 byr:1938 ecl:gry pid:037135813 hcl:#6b5442
+iyr:2010
+
+iyr:2017 hcl:4cc74b byr:1980 hgt:176in
+pid:460622356 ecl:xry eyr:2030
+
+hcl:z
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+
+iyr:2014 ecl:blu
+pid:332729196 hgt:63in
+eyr:2020
+hcl:#602927
+
+hcl:#7d3b0c pid:369981570 byr:1996 ecl:gry
+eyr:2024 iyr:2017
+
+pid:446117373 hgt:158cm
+iyr:2010 ecl:gry eyr:2024 hcl:#e54715
+
+cid:341 pid:842156559
+hgt:167cm hcl:#602927 byr:1939 ecl:amb iyr:2016
+
+byr:2017
+cid:176
+ecl:#9e42ae iyr:2029 pid:8965345 eyr:2038 hcl:z
+hgt:116
+
+eyr:2027 iyr:2014 hcl:#ceb3a1
+cid:280 pid:871521406 ecl:oth byr:1957 hgt:166cm
+
+cid:303 iyr:2019
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+hgt:184cm
+
+iyr:2015 byr:1936 cid:61 ecl:brn pid:307248029 hgt:172cm hcl:#18171d eyr:2029
+
+pid:708687506 ecl:brn hcl:#602927
+iyr:2014 byr:1987
+hgt:193cm
+eyr:2021
+
+ecl:gry
+iyr:2015 hcl:#efcc98 byr:1950
+cid:150 eyr:2023 pid:569864726
+hgt:161cm
+
+byr:1920 hcl:#602927 iyr:2018
+ecl:gry eyr:2020
+hgt:192cm pid:020336420
+
+hcl:#539335 byr:1949
+hgt:152cm
+cid:95 pid:002018679
+eyr:2030 iyr:2015 ecl:brn
+
+hcl:#b6652a eyr:2023
+pid:515291463 iyr:2013 byr:1990
+ecl:blu hgt:160cm
+
+eyr:2030 iyr:2012
+ecl:grn pid:416049447 hgt:188cm
+hcl:#a97842 byr:1976
+
+iyr:2017 hgt:61in ecl:oth byr:2001 eyr:2028
+hcl:#733820
+pid:078720467
+
+eyr:2021 hgt:151cm iyr:2020
+hcl:#efcc98 ecl:oth
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+pid:876231883
+
+iyr:2019 hcl:#ceb3a1 hgt:156in
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+
+pid:103964845 hgt:178cm cid:320 ecl:oth
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+
+ecl:brn byr:1920 pid:499363957
+cid:217 hcl:#341e13 hgt:164cm
+iyr:2017 eyr:2028
+
+ecl:brn pid:5837609946 iyr:2011
+byr:1971 eyr:2030 hgt:189cm
+hcl:#866857
+
+byr:1974 iyr:2015 hcl:#cfa07d
+hgt:190cm ecl:grn pid:330115418 eyr:2020 cid:173
+
+iyr:2010
+eyr:2024 byr:1943 pid:227557868
+cid:102 hgt:72in
+hcl:#6b5442
+
+hgt:151cm byr:1994
+pid:050723476
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+
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+hcl:#c5e354 hgt:192cm iyr:2019
+eyr:2027 pid:192177566
+
+ecl:hzl hcl:#c0946f byr:1997 pid:853199076 hgt:166cm
+iyr:2019
+eyr:2020
+cid:329
+
+eyr:2027 iyr:2029 hcl:#602927
+pid:#1b8593 byr:2028 hgt:172in ecl:grn
+
+eyr:2036 iyr:2030 ecl:utc
+pid:22330365 hcl:z byr:2016 hgt:65cm
+
+pid:936740771
+ecl:grn byr:1976
+hcl:#602927
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+
+eyr:2021 pid:415535681
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+
+hgt:193cm
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+
+ecl:gry byr:1996 cid:85 hgt:174cm iyr:2013 pid:444611265 hcl:#6b5442 eyr:2028
+
+pid:170343402
+iyr:2029
+hgt:167cm
+byr:2016 eyr:2034 ecl:hzl hcl:z cid:254
+
+hcl:4893d5 ecl:blu byr:1960
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+
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+cid:155 ecl:grn hcl:#602927
+
+hcl:#a97842 byr:1946
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+
+iyr:2020 hcl:#c0946f ecl:grn pid:601040247 cid:237 hgt:177cm eyr:2024
+byr:1941
+
+iyr:2014 byr:1959
+eyr:2028
+hcl:#fffffd
+ecl:#7df42b cid:165 hgt:68cm
+
+byr:1944 hcl:#18171d
+pid:009636175 hgt:155cm ecl:amb eyr:2032 iyr:2015
+
+byr:1987 hgt:150cm
+hcl:#b6652a eyr:2021
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+
+byr:1937 ecl:oth eyr:2022 hcl:#733820 pid:143694811 cid:175 hgt:150cm
+
+pid:562911401
+cid:80 hgt:61in byr:1922 eyr:2027 ecl:amb iyr:2014
+hcl:#602927
+
+iyr:2013 ecl:amb pid:826291674 hcl:#ceb3a1 eyr:2021 byr:1968 hgt:75in
+
+hcl:#5e0e07
+hgt:164cm pid:572114080 eyr:2028 iyr:2016
+byr:1922 ecl:oth
+
+ecl:blu eyr:2029 hgt:155cm
+byr:1950 hcl:#866857 cid:271 iyr:2015
+pid:216813084
+
+iyr:2018 byr:2009 cid:212 ecl:#71a98c pid:3467231102 hcl:z hgt:173cm
+eyr:2026
+
+eyr:1945 cid:302 iyr:2030
+hcl:z pid:0411732179
+byr:2004 hgt:165in
+ecl:grt
+
+iyr:2010 hgt:169cm
+hcl:#ceb3a1
+eyr:2022 pid:659709686 ecl:hzl
+byr:1931
+
+hcl:z pid:5077677466
+eyr:2021 hgt:184cm
+iyr:1973
+byr:2009 ecl:#35575e
+
+hgt:190cm cid:103 iyr:2018
+byr:1970 ecl:gry
+eyr:2028
+pid:549406360 hcl:#18171d
+
+byr:1964 eyr:2023 iyr:2015 hgt:174cm pid:305268492
+hcl:#b98e00 ecl:blu
+
+hgt:162cm
+ecl:brn iyr:2019 byr:1951
+cid:169 pid:755632568 eyr:2030 hcl:#ceb3a1
+
+iyr:2010 ecl:oth hgt:192cm eyr:2025
+hcl:#efcc98 pid:003868873 byr:1925
+
+hcl:z
+ecl:gmt hgt:62 eyr:1991
+byr:2012
+iyr:2025 pid:1835041269
+
+hgt:162
+iyr:2026 byr:2024
+pid:6463124513 hcl:#602927 ecl:oth eyr:2028
+
+hcl:bfb027 iyr:1945 byr:1989 eyr:1944 pid:826897563 ecl:dne cid:117 hgt:177
+
+hcl:#b6652a iyr:2013
+ecl:blu byr:1952 eyr:2020 pid:737726601 cid:308
+hgt:167cm
+
+eyr:2028 iyr:2012 hcl:#6b5442
+byr:1986 ecl:blu
+pid:365821409 hgt:180cm
+
+hgt:101 eyr:2037 pid:2457985649
+ecl:gmt
+hcl:4c0784 iyr:2029
+
+hcl:#341e13 iyr:1954 ecl:dne byr:2007
+eyr:2028 pid:552497791 hgt:189cm cid:263
+
+ecl:blu
+hgt:71in pid:360012597 eyr:2029 hcl:#18171d byr:1949
+iyr:2014
+
+hgt:164cm cid:237 iyr:2016 byr:1966
+hcl:#623a2f ecl:oth
+pid:129809894 eyr:2027
+
+hcl:a2243b eyr:2031
+ecl:#de9183
+byr:1982 hgt:109 iyr:1968 pid:848311277
+
+eyr:1950
+hcl:45470a byr:1983
+pid:82580746 cid:321
+hgt:191cm ecl:dne iyr:2013
+
+iyr:2018 ecl:blu eyr:2021
+byr:1983 pid:045613120
+
+hgt:164cm byr:1926
+hcl:#cfa07d
+eyr:2030
+iyr:2010
+pid:360787918 cid:61 ecl:amb
+
+pid:#d6dddd iyr:1967 ecl:gmt hcl:z byr:1947 eyr:1943 cid:93 hgt:97
+
+ecl:oth hgt:172cm
+hcl:#efcc98 byr:1957
+pid:729531506 iyr:2017
+eyr:2030
+
+ecl:#5a51b9 byr:2023 eyr:2021 iyr:2027
+pid:174cm hgt:80 hcl:6b4f6e
+
+hgt:157cm
+ecl:amb
+eyr:2020 pid:994733990 iyr:2020 cid:174 byr:1966
+hcl:#7d3b0c
+
+eyr:1986
+byr:2020 hcl:#c0946f
+pid:499981246
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+hgt:182cm ecl:#be1503 pid:9311657615 eyr:2005
+
+eyr:2035
+byr:1988 hgt:193cm
+iyr:2028 cid:128 hcl:#18171d ecl:utc pid:9743739773
+
+ecl:zzz hcl:z
+hgt:64cm pid:160cm byr:2026 eyr:1943 iyr:2028 cid:74
+
+ecl:oth
+pid:874577361
+iyr:2010 eyr:2021
+hgt:160cm hcl:#c0946f
+byr:1959
diff --git a/data/advent04a.txt b/data/advent04a.txt
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+ecl:gry pid:860033327 eyr:2020 hcl:#fffffd
+byr:1937 iyr:2017 cid:147 hgt:183cm
+
+iyr:2013 ecl:amb cid:350 eyr:2023 pid:028048884
+hcl:#cfa07d byr:1929
+
+hcl:#ae17e1 iyr:2013
+eyr:2024
+ecl:brn pid:760753108 byr:1931
+hgt:179cm
+
+hcl:#cfa07d eyr:2025 pid:166559648
+iyr:2011 ecl:brn hgt:59in
diff --git a/problems/day4.html b/problems/day4.html
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+<!DOCTYPE html>
+<html lang="en-us">
+<head>
+<meta charset="utf-8"/>
+<title>Day 4 - Advent of Code 2020</title>
+<!--[if lt IE 9]><script src="/static/html5.js"></script><![endif]-->
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+
+Oh, hello!  Funny seeing you here.
+
+I appreciate your enthusiasm, but you aren't going to find much down here.
+There certainly aren't clues to any of the puzzles.  The best surprises don't
+even appear in the source until you unlock them for real.
+
+Please be careful with automated requests; I'm not a massive company, and I can
+only take so much traffic.  Please be considerate so that everyone gets to play.
+
+If you're curious about how Advent of Code works, it's running on some custom
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+of the puzzles.
+
+The puzzles are most of the work; preparing a new calendar and a new set of
+puzzles each year takes all of my free time for 4-5 months. A lot of effort
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+enjoyed making it for you!
+
+If you'd like to hang out, I'm @ericwastl on Twitter.
+
+- Eric Wastl
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+-->
+<body>
+<header><div><h1 class="title-global"><a href="/">Advent of Code</a></h1><nav><ul><li><a href="/2020/about">[About]</a></li><li><a href="/2020/events">[Events]</a></li><li><a href="https://teespring.com/stores/advent-of-code" target="_blank">[Shop]</a></li><li><a href="/2020/settings">[Settings]</a></li><li><a href="/2020/auth/logout">[Log Out]</a></li></ul></nav><div class="user">Neil Smith <a href="/2020/support" class="supporter-badge" title="Advent of Code Supporter">(AoC++)</a> <span class="star-count">8*</span></div></div><div><h1 class="title-event">&nbsp;&nbsp;&nbsp;<span class="title-event-wrap">0x0000|</span><a href="/2020">2020</a><span class="title-event-wrap"></span></h1><nav><ul><li><a href="/2020">[Calendar]</a></li><li><a href="/2020/support">[AoC++]</a></li><li><a href="/2020/sponsors">[Sponsors]</a></li><li><a href="/2020/leaderboard">[Leaderboard]</a></li><li><a href="/2020/stats">[Stats]</a></li></ul></nav></div></header>
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+<div id="sponsor"><div class="quiet">Our <a href="/2020/sponsors">sponsors</a> help make Advent of Code possible:</div><div class="sponsor"><a href="https://medium.com/building-trayio" target="_blank" onclick="if(ga)ga('send','event','sponsor','sidebar',this.href);" rel="noopener">tray.io</a> - Building a platform that connects people with technology.</div></div>
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+<script>window.addEventListener('click', function(e,s,r){if(e.target.nodeName==='CODE'&&e.detail===3){s=window.getSelection();s.removeAllRanges();r=document.createRange();r.selectNodeContents(e.target);s.addRange(r);}});</script>
+<article class="day-desc"><h2>--- Day 4: Passport Processing ---</h2><p>You arrive at the airport only to realize that you grabbed your North Pole Credentials instead of your passport. While these documents are extremely similar, North Pole Credentials aren't issued by a country and therefore aren't actually valid documentation for travel in most of the world.</p>
+<p>It seems like you're not the only one having problems, though; a very long line has formed for the automatic passport scanners, and the delay could upset your travel itinerary.</p>
+<p>Due to some questionable network security, you realize you might be able to solve both of these problems at the same time.</p>
+<p>The automatic passport scanners are slow because they're having trouble <em>detecting which passports have all required fields</em>. The expected fields are as follows:</p>
+<ul>
+<li><code>byr</code> (Birth Year)</li>
+<li><code>iyr</code> (Issue Year)</li>
+<li><code>eyr</code> (Expiration Year)</li>
+<li><code>hgt</code> (Height)</li>
+<li><code>hcl</code> (Hair Color)</li>
+<li><code>ecl</code> (Eye Color)</li>
+<li><code>pid</code> (Passport ID)</li>
+<li><code>cid</code> (Country ID)</li>
+</ul>
+<p>Passport data is validated in batch files (your puzzle input). Each passport is represented as a sequence of <code>key:value</code> pairs separated by spaces or newlines. Passports are separated by blank lines.</p>
+<p>Here is an example batch file containing four passports:</p>
+<pre><code>ecl:gry pid:860033327 eyr:2020 hcl:#fffffd
+byr:1937 iyr:2017 cid:147 hgt:183cm
+
+iyr:2013 ecl:amb cid:350 eyr:2023 pid:028048884
+hcl:#cfa07d byr:1929
+
+hcl:#ae17e1 iyr:2013
+eyr:2024
+ecl:brn pid:760753108 byr:1931
+hgt:179cm
+
+hcl:#cfa07d eyr:2025 pid:166559648
+iyr:2011 ecl:brn hgt:59in
+</code></pre>
+<p>The first passport is <em>valid</em> - all eight fields are present. The second passport is <em>invalid</em> - it is missing <code>hgt</code> (the Height field).</p>
+<p>The third passport is interesting; the <em>only missing field</em> is <code>cid</code>, so it looks like data from North Pole Credentials, not a passport at all! Surely, nobody would mind if you made the system temporarily ignore missing <code>cid</code> fields.  Treat this "passport" as <em>valid</em>.</p>
+<p>The fourth passport is missing two fields, <code>cid</code> and <code>byr</code>. Missing <code>cid</code> is fine, but missing any other field is not, so this passport is <em>invalid</em>.</p>
+<p>According to the above rules, your improved system would report <code><em>2</em></code> valid passports.</p>
+<p>Count the number of <em>valid</em> passports - those that have all required fields. Treat <code>cid</code> as optional. <em>In your batch file, how many passports are valid?</em></p>
+</article>
+<p>Your puzzle answer was <code>247</code>.</p><article class="day-desc"><h2 id="part2">--- Part Two ---</h2><p>The line is moving more quickly now, but you overhear airport security talking about how passports with invalid data are getting through. Better add some data validation, quick!</p>
+<p>You can continue to ignore the <code>cid</code> field, but each other field has <span title="GLORY TO ARSTOTZKA">strict rules</span> about what values are valid for automatic validation:</p>
+<ul>
+<li><code>byr</code> (Birth Year) - four digits; at least <code>1920</code> and at most <code>2002</code>.</li>
+<li><code>iyr</code> (Issue Year) - four digits; at least <code>2010</code> and at most <code>2020</code>.</li>
+<li><code>eyr</code> (Expiration Year) - four digits; at least <code>2020</code> and at most <code>2030</code>.</li>
+<li><code>hgt</code> (Height) - a number followed by either <code>cm</code> or <code>in</code>:
+  <ul>
+  <li>If <code>cm</code>, the number must be at least <code>150</code> and at most <code>193</code>.</li>
+  <li>If <code>in</code>, the number must be at least <code>59</code> and at most <code>76</code>.</li>
+  </ul>
+</li>
+<li><code>hcl</code> (Hair Color) - a <code>#</code> followed by exactly six characters <code>0</code>-<code>9</code> or <code>a</code>-<code>f</code>.</li>
+<li><code>ecl</code> (Eye Color) - exactly one of: <code>amb</code> <code>blu</code> <code>brn</code> <code>gry</code> <code>grn</code> <code>hzl</code> <code>oth</code>.</li>
+<li><code>pid</code> (Passport ID) - a nine-digit number, including leading zeroes.</li>
+<li><code>cid</code> (Country ID) - ignored, missing or not.</li>
+</ul>
+<p>Your job is to count the passports where all required fields are both <em>present</em> and <em>valid</em> according to the above rules. Here are some example values:</p>
+<pre><code>byr valid:   2002
+byr invalid: 2003
+
+hgt valid:   60in
+hgt valid:   190cm
+hgt invalid: 190in
+hgt invalid: 190
+
+hcl valid:   #123abc
+hcl invalid: #123abz
+hcl invalid: 123abc
+
+ecl valid:   brn
+ecl invalid: wat
+
+pid valid:   000000001
+pid invalid: 0123456789
+</code></pre>
+<p>Here are some invalid passports:</p>
+<pre><code>eyr:1972 cid:100
+hcl:#18171d ecl:amb hgt:170 pid:186cm iyr:2018 byr:1926
+
+iyr:2019
+hcl:#602927 eyr:1967 hgt:170cm
+ecl:grn pid:012533040 byr:1946
+
+hcl:dab227 iyr:2012
+ecl:brn hgt:182cm pid:021572410 eyr:2020 byr:1992 cid:277
+
+hgt:59cm ecl:zzz
+eyr:2038 hcl:74454a iyr:2023
+pid:3556412378 byr:2007
+</code></pre>
+<p>Here are some valid passports:</p>
+<pre><code>pid:087499704 hgt:74in ecl:grn iyr:2012 eyr:2030 byr:1980
+hcl:#623a2f
+
+eyr:2029 ecl:blu cid:129 byr:1989
+iyr:2014 pid:896056539 hcl:#a97842 hgt:165cm
+
+hcl:#888785
+hgt:164cm byr:2001 iyr:2015 cid:88
+pid:545766238 ecl:hzl
+eyr:2022
+
+iyr:2010 hgt:158cm hcl:#b6652a ecl:blu byr:1944 eyr:2021 pid:093154719
+</code></pre>
+<p>Count the number of <em>valid</em> passports - those that have all required fields <em>and valid values</em>. Continue to treat <code>cid</code> as optional. <em>In your batch file, how many passports are valid?</em></p>
+</article>
+<p>Your puzzle answer was <code>145</code>.</p><p class="day-success">Both parts of this puzzle are complete! They provide two gold stars: **</p>
+<p>At this point, you should <a href="/2020">return to your Advent calendar</a> and try another puzzle.</p>
+<p>If you still want to see it, you can <a href="4/input" target="_blank">get your puzzle input</a>.</p>
+<p>You can also <span class="share">[Share<span class="share-content">on
+  <a href="https://twitter.com/intent/tweet?text=I%27ve+completed+%22Passport+Processing%22+%2D+Day+4+%2D+Advent+of+Code+2020&amp;url=https%3A%2F%2Fadventofcode%2Ecom%2F2020%2Fday%2F4&amp;related=ericwastl&amp;hashtags=AdventOfCode" target="_blank">Twitter</a>
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+></span>]</span> this puzzle.</p>
+</main>
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diff --git a/stack.yaml b/stack.yaml
index 4659b84..6066fde 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -38,6 +38,7 @@ packages:
 - advent01
 - advent02
 - advent03
+- advent04
 
 # Dependency packages to be pulled from upstream that are not in the resolver.
 # These entries can reference officially published versions as well as