49 lines
1.5 KiB
Haskell
49 lines
1.5 KiB
Haskell
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removeCancelled :: String -> String
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removeCancelled str =
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let (_, removed) = foldl (\(prev, rs) curr ->
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case prev of
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'!' -> ('\0', rs)
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'\0' -> (curr, rs)
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_ -> (curr, prev : rs))
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(head str, "") (tail str)
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in reverse $ filter (/= '\0') removed
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removeGarbage :: String -> String
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removeGarbage str =
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let (_, removed) = foldl (\(isGarbage, rs) curr ->
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if isGarbage
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then (curr /= '>', rs)
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else (curr == '<',
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if curr == '<'
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then rs
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else curr : rs))
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(False, "") str
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in reverse $ filter (/= ',') removed
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countNonGarbage :: String -> Int
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countNonGarbage str =
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let (_, removed) = foldl (\(isGarbage, rs) curr ->
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if isGarbage
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then (curr /= '>',
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if curr == '>'
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then rs
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else curr : rs)
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else (curr == '<', rs))
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(False, "") str
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in length removed
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countGroups :: String -> Int
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countGroups str =
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let (_, total) = foldl (\(score, acc) curr ->
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case curr of
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'{' -> (score + 1, acc + score)
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'}' -> (score - 1, acc))
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(1, 0) str
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in total
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main :: IO ()
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main = do
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input <- readFile "9.txt"
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print $ countGroups . removeGarbage . removeCancelled $ input
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print $ countNonGarbage . removeCancelled $ input
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