There are a few different kinds of trees, but if you only need to
store data on the leaves, that representation will work. As for your
sumTree function, you are indeed missing a case...consider sumTree
(Leaf 3)! Once you deal with that case, the other two can actually be
combined (since sum [] = 0).
2008/7/21 Ryan Bloor
hi
I was curious as to whether my implementation of a Rose Tree and a sumTree function was correct. The aumTree adds up the elements of a tree.
data Tree a = Leaf a | Node [Tree a]
sumTree :: Tree Int -> Int sumTree (Node []) = 0 sumTree (Node xs) = sum (map sumTree xs)
The problem with this is I get a pattern matching error. Am I representing trees right... see below.
Also, would an empty tree be represented by ... Node [] with this implementation? How would I represent a tree of the form... Tree (Node 2(Node 6 Empty Empty) Empty) taken from a binary one. Like this? Node [ [Leaf 2], Node [ Leaf 6,Node[],Node[] ], Node[] ]
Ryan
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