Solution: Note that the diameter may not pass through the root-node (as shown above)
Also, the ends of the diameter will be such that one of them lies in the
left subtree of a node and the other end lies in the right subtree of the same node.
Otherwise the diameter will tend to appear like a knot.
For example, if the diameter of the above tree were to be: 9 -> 14 -> 7 -> 14 -> 22,
then 14 -> 7 -> -> 14 nodes would appear like a knot and that is not allowed to be in a diameter.
So, there will be one node whose left and right legs of deepest height would form the diameter.
Our task is to find that node for which 1 + diameter(left) + diameter(right) is the maximum.
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