0199 Binary Tree Right Side View.py

# 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
class Solution:
    def rightSideView(self, root: Optional[TreeNode]) -> List[int]:
        """
        https://leetcode.com/problems/binary-tree-right-side-view/
        https://youtu.be/d4zLyf32e3I
        
        199. Binary Tree Right Side View
        Medium

        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:
        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
        """