Binary tree right side view and Lowest common ancestor
Consider a binary tree. If you look at it from the right-hand side, return a list of values of the nodes that are visible from the top to the bottom.
Example 1: Input: [10, 5, 15, null, 7, null, 20] Output: [10, 15, 20] Explanation: 10 <--- / \ 5 15 <--- \ \ 7 20 <---
Example 2: Input: [3, 9, 8, 4, null, null, 7] Output: [3, 8, 7] Explanation: 3 <--- / \ 9 8 <--- / \ 4 7 <---