22 lines
552 B
Haskell
22 lines
552 B
Haskell
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-- This is the same solution as in Problem 11
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data ListItem a = Single a | Multiple Int a deriving (Show)
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getListItem :: (Int, a) -> ListItem a
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getListItem (1, x) = Single x
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getListItem (n, x) = Multiple n x
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encode :: (Eq a) => [a] -> [(Int, a)]
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encode =
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foldr
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( \x acc -> case acc of
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[] -> [(1, x)]
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(hd@(hd_n, hd_a) : tl) ->
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if x == hd_a
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then (hd_n + 1, hd_a) : tl
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else (1, x) : hd : tl
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)
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[]
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encodeModified :: (Eq a) => [a] -> [ListItem a]
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encodeModified = map getListItem <$> encode
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