On Thu, May 6, 2010 at 9:51 PM, legajid
Oops, mistake in sender name.
Hi, i wanted to write an algorithm for loading a binary tree, then get the values in order and other operations.
So, i created a data type : data AR a = R a (AR a) (AR a) | N deriving (Show, Ord, Eq) for an example : R 30 (R 10 (N) (R 20 N N )) (R 40 (N) (R 50 N N ))
the main problem i had is : how to update such a complex value, to add another one. After hours of trying (and error !) my solution is : find where to insert the new value, then read the whole tree and copy its values, except for the one for insert.
Let's say your tree is either empty or is a node that holds a value and two subtrees, one for values that are smaller and one for values that are greater. What if you want to insert a value into an empty tree ? You make a node with the given value and the two subtrees empty ins v N = R v N N what is the tree isn't empty ? two possibilities: - the value to insert is smaller than the node's value -> replace the subtree of smaller values by the result of inserting the value into that subtree - it's bigger ins v (R v' s1 s2) | v < v' = R v' (ins v s1) s2 | v > v' = R v' s1 (ins v s2) question : what to do if v == v' ? I leave the question to you :) That's it :)