63 lines
2.3 KiB
Haskell
63 lines
2.3 KiB
Haskell
import System.Environment
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data Color =
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Red | Black
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data Tree =
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Leaf
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| Node Color Tree Int Bool Tree
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fold :: (Int -> Bool -> σ -> σ) -> Tree -> 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 :: Int -> Bool -> Tree -> Tree -> Tree
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balance1 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 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 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 :: Int -> Bool -> Tree -> Tree -> Tree
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balance2 kv vv t (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 kv vv t (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 kv vv t (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 -> Bool
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is_red (Node Red _ _ _ _) = True
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is_red _ = False
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ins :: Tree -> Int -> Bool -> Tree
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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 kx < ky then Node Red (ins a kx vx) ky vy b
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else if 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 kx < ky then
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(if is_red a then balance1 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 ky < kx then
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(if is_red b then balance2 ky vy a (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 -> Tree
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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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mk_Map_aux :: Int -> Tree -> Tree
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mk_Map_aux 0 m = m
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mk_Map_aux n m = let n' = n-1 in mk_Map_aux n' (insert m n' (n' `mod` 10 == 0))
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mk_Map n = mk_Map_aux n Leaf
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main = do
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[arg] <- getArgs
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let m = mk_Map $ read arg
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let v = fold (\_ v r -> if v then r + 1 else r) m 0
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print v
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