This weekend I completed the data structures portion of the **Cracking the Coding Interview Questions** on HackerRank. One of the programming challenges, **validating a binary search tree**, taught me how to verify a binary search tree is valid and I wanted to share my solution using Python.

In a recent programming challenge I was asked to code an inorder traversal of a binary search tree to print the values of its keys in the correct order. An order traversal of a binary search tree will print the keys of the node's left sub-tree, followed by the node's key, followed by the keys of the node's right sub-tree. I also show how to create a binary search tree in Python using level order traversal (like breadth-first search) and a list of ordered keys.

Read More