# 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 <---
```

We use **postorder** tree traversal.

- We maintain the current depth in the recurrent calls;
- Use vector
`vals`

to store rightmost value at depth`i`

; - The nodes at the same depth will be visited from left to right. The key to ensure this is to traverse left subtree
*before*the right one. This will allow to overwrite the value at the same depth in`vals`

; - Is is easy to see that preoreder or inorder traversal would work as well.

Code: