Haskell, (削除) 1077 (削除ここまで) (削除) 1069 (削除ここまで) 1068 bytes

z s=last$"Arstotzka":[filter(/=s)[l,r]!!0|(l,_:r)<-span(<'~')<$>lines"Baton Rouge~Louisiana\nIndianapolis~Indiana\nColumbus~Ohio\nMontgomery~Alabama\nHelena~Montana\nDenver~Colorado\nBoise~Idaho\nAustin~Texas\nBoston~Massachusetts\nAlbany~New York\nTallahassee~Florida\nSanta Fe~New Mexico\nNashville~Tennessee\nTrenton~New Jersey\nJefferson~Missouri\nRichmond~Virginia\nPierre~South Dakota\nHarrisburg~Pennsylvania\nAugusta~Maine\nProvidence~Rhode Island\nDover~Delaware\nConcord~New Hampshire\nMontpelier~Vermont\nHartford~Connecticut\nTopeka~Kansas\nSaint Paul~Minnesota\nJuneau~Alaska\nLincoln~Nebraska\nRaleigh~North Carolina\nMadison~Wisconsin\nOlympia~Washington\nPhoenix~Arizona\nLansing~Michigan\nHonolulu~Hawaii\nJackson~Mississippi\nSpringfield~Illinois\nColumbia~South Carolina\nAnnapolis~Maryland\nCheyenne~Wyoming\nSalt Lake City~Utah\nAtlanta~Georgia\nBismarck~North Dakota\nFrankfort~Kentucky\nSalem~Oregon\nLittle Rock~Arkansas\nDes Moines~Iowa\nSacramento~California\nOklahoma City~Oklahoma\nCharleston~West Virginia\nCarson City~Nevada",elem s[l,r]]

Try it online!

After wasting a lot of time trying to golf an implementation of Huffman coding I realized the straightforward approach is probably shorter. Ah, well.

EDIT: Thanks to @Laikoni for taking off 8 bytes! EDIT: Thanks again Laikoni for that additional byte. Good idea to use '~'

Haskell, (削除) 1077 (削除ここまで) (削除) 1069 (削除ここまで) (削除) 1068 (削除ここまで) 1063 bytes

z s=last$"Arstotzka":[last$l:[r|s==l]|(l,_:r)<-span(<'~')<$>lines"Baton Rouge~Louisiana\nIndianapolis~Indiana\nColumbus~Ohio\nMontgomery~Alabama\nHelena~Montana\nDenver~Colorado\nBoise~Idaho\nAustin~Texas\nBoston~Massachusetts\nAlbany~New York\nTallahassee~Florida\nSanta Fe~New Mexico\nNashville~Tennessee\nTrenton~New Jersey\nJefferson~Missouri\nRichmond~Virginia\nPierre~South Dakota\nHarrisburg~Pennsylvania\nAugusta~Maine\nProvidence~Rhode Island\nDover~Delaware\nConcord~New Hampshire\nMontpelier~Vermont\nHartford~Connecticut\nTopeka~Kansas\nSaint Paul~Minnesota\nJuneau~Alaska\nLincoln~Nebraska\nRaleigh~North Carolina\nMadison~Wisconsin\nOlympia~Washington\nPhoenix~Arizona\nLansing~Michigan\nHonolulu~Hawaii\nJackson~Mississippi\nSpringfield~Illinois\nColumbia~South Carolina\nAnnapolis~Maryland\nCheyenne~Wyoming\nSalt Lake City~Utah\nAtlanta~Georgia\nBismarck~North Dakota\nFrankfort~Kentucky\nSalem~Oregon\nLittle Rock~Arkansas\nDes Moines~Iowa\nSacramento~California\nOklahoma City~Oklahoma\nCharleston~West Virginia\nCarson City~Nevada",s==l||s==r]

Try it online!

After wasting a lot of time trying to golf an implementation of Huffman coding I realized the straightforward approach is probably shorter. Ah, well.

EDIT: Thanks to @Laikoni for taking off 8 bytes!

EDIT: Thanks again Laikoni for that additional byte. Good idea to use '~'

EDIT: Thanks to Laikoni for taking off those 5 bytes!

Haskell, (削除) 1077 (削除ここまで) 1069 bytes

z s=last$"Arstotzka":[filter(/=s)[l,r]!!0|(l,_:r)<-span(/=',')<$>lines"Baton Rouge,Louisiana\nIndianapolis,Indiana\nColumbus,Ohio\nMontgomery,Alabama\nHelena,Montana\nDenver,Colorado\nBoise,Idaho\nAustin,Texas\nBoston,Massachusetts\nAlbany,New York\nTallahassee,Florida\nSanta Fe,New Mexico\nNashville,Tennessee\nTrenton,New Jersey\nJefferson,Missouri\nRichmond,Virginia\nPierre,South Dakota\nHarrisburg,Pennsylvania\nAugusta,Maine\nProvidence,Rhode Island\nDover,Delaware\nConcord,New Hampshire\nMontpelier,Vermont\nHartford,Connecticut\nTopeka,Kansas\nSaint Paul,Minnesota\nJuneau,Alaska\nLincoln,Nebraska\nRaleigh,North Carolina\nMadison,Wisconsin\nOlympia,Washington\nPhoenix,Arizona\nLansing,Michigan\nHonolulu,Hawaii\nJackson,Mississippi\nSpringfield,Illinois\nColumbia,South Carolina\nAnnapolis,Maryland\nCheyenne,Wyoming\nSalt Lake City,Utah\nAtlanta,Georgia\nBismarck,North Dakota\nFrankfort,Kentucky\nSalem,Oregon\nLittle Rock,Arkansas\nDes Moines,Iowa\nSacramento,California\nOklahoma City,Oklahoma\nCharleston,West Virginia\nCarson City,Nevada",elem s[l,r]]

Try it online!

After wasting a lot of time trying to golf an implementation of Huffman coding I realized the straightforward approach is probably shorter. Ah, well.

EDIT: Thanks to @Laikoni for taking off 8 bytes!

Haskell, (削除) 1077 (削除ここまで) (削除) 1069 (削除ここまで) 1068 bytes

z s=last$"Arstotzka":[filter(/=s)[l,r]!!0|(l,_:r)<-span(<'~')<$>lines"Baton Rouge~Louisiana\nIndianapolis~Indiana\nColumbus~Ohio\nMontgomery~Alabama\nHelena~Montana\nDenver~Colorado\nBoise~Idaho\nAustin~Texas\nBoston~Massachusetts\nAlbany~New York\nTallahassee~Florida\nSanta Fe~New Mexico\nNashville~Tennessee\nTrenton~New Jersey\nJefferson~Missouri\nRichmond~Virginia\nPierre~South Dakota\nHarrisburg~Pennsylvania\nAugusta~Maine\nProvidence~Rhode Island\nDover~Delaware\nConcord~New Hampshire\nMontpelier~Vermont\nHartford~Connecticut\nTopeka~Kansas\nSaint Paul~Minnesota\nJuneau~Alaska\nLincoln~Nebraska\nRaleigh~North Carolina\nMadison~Wisconsin\nOlympia~Washington\nPhoenix~Arizona\nLansing~Michigan\nHonolulu~Hawaii\nJackson~Mississippi\nSpringfield~Illinois\nColumbia~South Carolina\nAnnapolis~Maryland\nCheyenne~Wyoming\nSalt Lake City~Utah\nAtlanta~Georgia\nBismarck~North Dakota\nFrankfort~Kentucky\nSalem~Oregon\nLittle Rock~Arkansas\nDes Moines~Iowa\nSacramento~California\nOklahoma City~Oklahoma\nCharleston~West Virginia\nCarson City~Nevada",elem s[l,r]]

Try it online!

After wasting a lot of time trying to golf an implementation of Huffman coding I realized the straightforward approach is probably shorter. Ah, well.

EDIT: Thanks to @Laikoni for taking off 8 bytes! EDIT: Thanks again Laikoni for that additional byte. Good idea to use '~'

Haskell, 1077 bytes

z s=last$"Arstotzka":[filter(/=s)[l,r]!!0|(l,r)<-fmap tail.span(/=',')<$>lines"Baton Rouge,Louisiana\nIndianapolis,Indiana\nColumbus,Ohio\nMontgomery,Alabama\nHelena,Montana\nDenver,Colorado\nBoise,Idaho\nAustin,Texas\nBoston,Massachusetts\nAlbany,New York\nTallahassee,Florida\nSanta Fe,New Mexico\nNashville,Tennessee\nTrenton,New Jersey\nJefferson,Missouri\nRichmond,Virginia\nPierre,South Dakota\nHarrisburg,Pennsylvania\nAugusta,Maine\nProvidence,Rhode Island\nDover,Delaware\nConcord,New Hampshire\nMontpelier,Vermont\nHartford,Connecticut\nTopeka,Kansas\nSaint Paul,Minnesota\nJuneau,Alaska\nLincoln,Nebraska\nRaleigh,North Carolina\nMadison,Wisconsin\nOlympia,Washington\nPhoenix,Arizona\nLansing,Michigan\nHonolulu,Hawaii\nJackson,Mississippi\nSpringfield,Illinois\nColumbia,South Carolina\nAnnapolis,Maryland\nCheyenne,Wyoming\nSalt Lake City,Utah\nAtlanta,Georgia\nBismarck,North Dakota\nFrankfort,Kentucky\nSalem,Oregon\nLittle Rock,Arkansas\nDes Moines,Iowa\nSacramento,California\nOklahoma City,Oklahoma\nCharleston,West Virginia\nCarson City,Nevada",elem s[l,r]]

Try it online!

After wasting a lot of time trying to golf an implementation of Huffman coding I realized the straightforward approach is probably shorter. Ah, well.

Haskell, (削除) 1077 (削除ここまで) 1069 bytes

z s=last$"Arstotzka":[filter(/=s)[l,r]!!0|(l,_:r)<-span(/=',')<$>lines"Baton Rouge,Louisiana\nIndianapolis,Indiana\nColumbus,Ohio\nMontgomery,Alabama\nHelena,Montana\nDenver,Colorado\nBoise,Idaho\nAustin,Texas\nBoston,Massachusetts\nAlbany,New York\nTallahassee,Florida\nSanta Fe,New Mexico\nNashville,Tennessee\nTrenton,New Jersey\nJefferson,Missouri\nRichmond,Virginia\nPierre,South Dakota\nHarrisburg,Pennsylvania\nAugusta,Maine\nProvidence,Rhode Island\nDover,Delaware\nConcord,New Hampshire\nMontpelier,Vermont\nHartford,Connecticut\nTopeka,Kansas\nSaint Paul,Minnesota\nJuneau,Alaska\nLincoln,Nebraska\nRaleigh,North Carolina\nMadison,Wisconsin\nOlympia,Washington\nPhoenix,Arizona\nLansing,Michigan\nHonolulu,Hawaii\nJackson,Mississippi\nSpringfield,Illinois\nColumbia,South Carolina\nAnnapolis,Maryland\nCheyenne,Wyoming\nSalt Lake City,Utah\nAtlanta,Georgia\nBismarck,North Dakota\nFrankfort,Kentucky\nSalem,Oregon\nLittle Rock,Arkansas\nDes Moines,Iowa\nSacramento,California\nOklahoma City,Oklahoma\nCharleston,West Virginia\nCarson City,Nevada",elem s[l,r]]

Try it online!

After wasting a lot of time trying to golf an implementation of Huffman coding I realized the straightforward approach is probably shorter. Ah, well.

EDIT: Thanks to @Laikoni for taking off 8 bytes!