Binary Tree Right Side View
Part of Practice: Levels & BST Rules
Imagine standing to the right of a binary tree and looking at it sideways: at each depth you can only see the node closest to you. Given the root, return the values of the visible nodes from top to bottom.
The tree has 0 to 100 nodes. Note that a left child can be visible if nothing at its depth sits further right.
Examples
- Input:
- root = [1,2,3,null,5,null,4]
- Output:
- [1,3,4]
The levels are [1], [2,3], [5,4]. The rightmost node of each level is 1, then 3, then 4; the 5 sits to the left of 4 at the same depth, so it is hidden.
- Input:
- root = [1,2]
- Output:
- [1,2]
2 is a left child, but nothing at its depth is further right, so it is visible.
- Input:
- root = []
- Output:
- []
Hints
One at a time — struggle first, peek second.
Your thinking space — verify on LeetCode, then mark it.