How to determine whether a binary tree is complete?

Question

A complete binary tree is defined as a binary tree in which every level, except possibly the deepest, is completely filled. At deepest level, all nodes must be as far left a

Answer 1

You can do it recursively by comparing the heights of each node's children. There may be at most one node where the left child has a height exactly one greater than the right child; all other nodes must be perfectly balanced.