Binary Search Tree Iterator is an example of null problems. In this post we will see how we can solve in Javascript.

Problem Description

Implement an iterator over a binary search tree (BST). Your iterator will be initialized with the root node of a BST.

Calling next() will return the next smallest number in the BST.

Note: next() and hasNext() should run in average O(1) time and uses O(h) memory, where h is the height of the tree.

If you have different approach in mind or have any suggestion for this implementation feel free to share in the comment below. Thanks!