# 199 Binary Tree Right Side View

Given the `root` of 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 1:

``````  1  <=
/ \
2   3  <=
\   \
5   4  <=

Input: root = [1,2,3,null,5,null,4]
Output: [1,3,4]
``````

Example 2:

``````Input: root = [1,null,3]
Output: [1,3]
``````

Example 3:

``````Input: root = []
Output: []
``````

Constraints:

• The number of nodes in the tree is in the range `[0, 100]`.
• `-100 <= Node.val <= 100`
 `````` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 `````` ``````# Definition for a binary tree node. # class TreeNode: # def __init__(self, val=0, left=None, right=None): # self.val = val # self.left = left # self.right = right from collections import deque class Solution: def rightSideView(self, root: Optional[TreeNode]) -> List[int]: if not root: return [] q = deque([root]) res = [] while q: res.append(q[-1].val) size = len(q) for i in range(size): node = q.popleft() if node.left: q.append(node.left) if node.right: q.append(node.right) return res``````