Day 6 of Leetcode February Challenge !

Given a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom.

Example:

Input: [1,2,3,null,5,null,4]
Output: [1, 3, 4]
Explanation:
   1            <---
 /   \
2     3         <---
 \     \
  5     4       <---