#Tree Traversal

Given the root of a binary tree, return the zigzag level order traversal of its nodes' values (i.e., from left to right, then right to left for the next level and alternate between). (LeetCode 103)

Describe different tree traversal techniques and validate a binary tree's structure. Discuss the time and space complexity of your approach.

Describe how to achieve vertical order traversal of a binary tree. Include considerations for scalability and fault tolerance in your design.

Count the total number of nodes in a binary tree. Use inorder traversal as your approach.