Binary tree

Question

Consider a binary tree for every node | P - Q | <= 2. P represents number of nodes in left subtree of S and Q represents number of nodes in right subtree of S for h > 0. The minimum number of nodes present in such tree of height h = 4 ( Root at 0 level)

Comments

Please Discuss General Approach of it

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Total no of node=no of nodes in a complete binary tree of height (h-2 )+2

So here answer is 9