32 lines
896 B
Text
32 lines
896 B
Text
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main :: [sys_message]
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main = [Stdout (lay [show (f example)
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| f <- [preorder,inorder,postorder,levelorder]])]
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example :: tree num
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example = Node 1 (Node 2 (Node 4 (leaf 7) Nilt)
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(leaf 5))
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(Node 3 (Node 6 (leaf 8) (leaf 9)) Nilt)
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tree * ::= Nilt | Node * (tree *) (tree *)
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leaf :: *->tree *
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leaf k = Node k Nilt Nilt
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preorder :: tree *->[*]
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preorder Nilt = []
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preorder (Node v l r) = v : preorder l ++ preorder r
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inorder :: tree *->[*]
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inorder Nilt = []
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inorder (Node v l r) = inorder l ++ v : inorder r
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postorder :: tree *->[*]
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postorder Nilt = []
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postorder (Node v l r) = postorder l ++ postorder r ++ [v]
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levelorder :: tree *->[*]
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levelorder t = f [t]
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where f [] = []
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f (Nilt:xs) = f xs
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f (Node v l r:xs) = v : f (xs++[l,r])
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