C# solution for Leetcode question: Binary Search Tree Iterator (difficulty : medium)

Source:
https://leetcode.com/problems/binary-search-tree-iterator/#/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.

My C# solution is here:

https://github.com/jiajionline/LeetcodeSolutionWithMultipleLanguages/tree/master/Binary%20Search%20Tree%20Iterator