Count Complete Tree Nodes | Python

The approach to counting the number of nodes in a complete binary tree is to use a recursive algorithm. The basic idea is to first determine the depth of the left and right subtrees of the current node. If the left and right depths are equal, it means that the left subtree is a complete tree and the number of nodes in the right subtree can be recursively calculated. If the left and right depths are not equal, it means that the right subtree is a complete tree and the number of nodes in the left subtree can be recursively calculated.

This process is then repeated for each subtree until the entire tree has been traversed. At each step, the number of nodes in the complete subtree can be calculated using the formula 2^depth - 1, where depth is the depth of the subtree. This is because a complete binary tree with depth levels will have 2^depth - 1 nodes.

By combining the number of nodes in the complete subtree and the number of nodes in the non-complete subtree, we can calculate the total number of nodes in the tree. This is done by adding the number of nodes in the complete subtree to the number of nodes in the non-complete subtree, which is calculated recursively.

This method has a time complexity of O(log(n)^2) where n is the number of nodes in the tree.