81 lines
3.1 KiB
Haskell
81 lines
3.1 KiB
Haskell
{-# LANGUAGE BangPatterns #-}
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import System.Environment
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data Color =
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Red | Black
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data Tree α β =
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Leaf
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| Node Color (Tree α β) α β (Tree α β)
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fold :: (α -> β -> σ -> σ) -> Tree α β -> σ -> σ
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fold _ Leaf b = b
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fold f (Node _ l k v r) b = fold f r (f k v (fold f l b))
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balance1 :: Tree α β -> Tree α β -> Tree α β
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balance1 (Node _ _ kv vv t) (Node _ (Node Red l kx vx r₁) ky vy r₂) = Node Red (Node Black l kx vx r₁) ky vy (Node Black r₂ kv vv t)
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balance1 (Node _ _ kv vv t) (Node _ l₁ ky vy (Node Red l₂ kx vx r)) = Node Red (Node Black l₁ ky vy l₂) kx vx (Node Black r kv vv t)
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balance1 (Node _ _ kv vv t) (Node _ l ky vy r) = Node Black (Node Red l ky vy r) kv vv t
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balance1 _ _ = Leaf
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balance2 :: Tree α β -> Tree α β -> Tree α β
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balance2 (Node _ t kv vv _) (Node _ (Node Red l kx₁ vx₁ r₁) ky vy r₂) = Node Red (Node Black t kv vv l) kx₁ vx₁ (Node Black r₁ ky vy r₂)
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balance2 (Node _ t kv vv _) (Node _ l₁ ky vy (Node Red l₂ kx₂ vx₂ r₂)) = Node Red (Node Black t kv vv l₁) ky vy (Node Black l₂ kx₂ vx₂ r₂)
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balance2 (Node _ t kv vv _) (Node _ l ky vy r) = Node Black t kv vv (Node Red l ky vy r)
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balance2 _ _ = Leaf
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is_red :: Tree α β -> Bool
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is_red (Node Red _ _ _ _) = True
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is_red _ = False
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lt x y = x < y
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ins :: Ord α => Tree α β -> α -> β -> Tree α β
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ins Leaf kx vx = Node Red Leaf kx vx Leaf
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ins (Node Red a ky vy b) kx vx =
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(if lt kx ky then Node Red (ins a kx vx) ky vy b
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else if lt ky kx then Node Red a ky vy (ins b kx vx)
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else Node Red a ky vy (ins b kx vx))
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ins (Node Black a ky vy b) kx vx =
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if lt kx ky then
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(if is_red a then balance1 (Node Black Leaf ky vy b) (ins a kx vx)
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else Node Black (ins a kx vx) ky vy b)
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else if lt ky kx then
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(if is_red b then balance2 (Node Black a ky vy Leaf) (ins b kx vx)
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else Node Black a ky vy (ins b kx vx))
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else Node Black a kx vx b
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set_black :: Tree α β -> Tree α β
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set_black (Node _ l k v r) = Node Black l k v r
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set_black e = e
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insert t k v =
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if is_red t then set_black (ins t k v)
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else ins t k v
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type Map = Tree Int Bool
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mk_Map_aux :: Int -> Int -> Map -> [Map] -> [Map]
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mk_Map_aux freq 0 m r = m:r
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mk_Map_aux freq n m r =
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let n' = n-1 in
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-- We try to stay away from language-specific optimizations,
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-- but in this instance strictness is imperative to ensure
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-- that `freq` is indeed respected instead of keeping all
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-- binary trees alive in thunks.
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let !m' = (insert m n' (n' `mod` 10 == 0)) in
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let !r' = if (n' `mod` freq == 0) then (m':r) else r in
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mk_Map_aux freq n' m' r'
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mk_Map n freq = mk_Map_aux freq n Leaf []
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myLen :: [Map] -> Int -> Int
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myLen ((Node _ _ _ _ _) : xs) r = myLen xs (r+1)
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myLen (_ : xs) r = myLen xs r
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myLen [] r = r
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main = do
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[n, freq] <- getArgs
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let mList = mk_Map (read n) (read freq)
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let v = fold (\_ v r -> if v then r + 1 else r) (head mList) 0 :: Int
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print (show (myLen mList 0) ++ " " ++ show v)
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