36 lines
1.1 KiB
Haskell
36 lines
1.1 KiB
Haskell
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import Data.List -- sort
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import Data.Map (Map)
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import qualified Data.Map.Strict as Map.Strict
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import qualified Data.Map as Map
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mapTuple :: (a -> b) -> (a, a) -> (b, b)
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mapTuple f (a1, a2) = (f a1, f a2)
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countH :: Ord a => Map a Integer -> [a] -> Map a Integer
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countH m (x:xs) = countH newmap xs
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where newmap = Map.Strict.insertWith (+) x 1 m
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countH m _ = m
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count :: Ord a => [a] -> Map a Integer
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count = countH Map.empty
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applyToSecond :: (b->c) -> (a, b) -> (a, c)
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applyToSecond f (x, y) = (x, f y)
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toColumnsH :: [a] -> [a] -> [a] -> ([a], [a])
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toColumnsH ls rs (x:xs) = toColumnsH rs (ls++[x]) xs
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toColumnsH ls rs _ = (ls, rs)
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toColumns :: [a] -> ([a], [a])
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toColumns = toColumnsH [] []
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similarityH :: Integer -> Map Integer Integer -> [Integer] -> Integer
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similarityH acc m (x:xs) = similarityH (acc + x * (Map.findWithDefault 0 x m)) m xs
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similarityH acc m _ = acc
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similarity :: ([Integer], Map Integer Integer) -> Integer
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similarity (xs, m) = similarityH 0 m xs
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main = interact $ show . similarity . applyToSecond count . mapTuple sort . toColumns . map read . words
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