Medium : https://leetcode.com/problems/binary-tree-right-side-view/ 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 <--- …