21 lines
601 B
Haskell
21 lines
601 B
Haskell
data Tree a = Empty | Branch a (Tree a) (Tree a)
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deriving (Show, Eq)
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isMirror :: Tree a -> Tree a -> Bool
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isMirror Empty Empty = True
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isMirror (Branch _ l1 r1) (Branch _ l2 r2) = isMirror l1 r2 && isMirror r1 l2
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isMirror _ _ = False
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symmetric :: (Eq a) => Tree a -> Bool
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symmetric Empty = True
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symmetric (Branch _ l r) = isMirror l r
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add :: (Ord a) => a -> Tree a -> Tree a
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add x Empty = Branch x Empty Empty
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add x t@(Branch v l r) = case compare x v of
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LT -> Branch v (add x l) r
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GT -> Branch v l (add x r)
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EQ -> t
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construct :: (Ord a) => [a] -> Tree a
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construct = foldl (flip add) Empty
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