199. Binary Tree Right Side View Leetcode Python

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.

For example:
Given the following binary tree,

# Definition for a  binary tree node
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    # @param root, a tree node
    # @return a list of integers
    def levelorder(self, root, level, res):
        if root:
            if len(res)< level + 1:
                res.append([])
            res[level].append(root.val)
            self.levelorder(root.left, level+1, res)
            self.levelorder(root.right, level+1, res)
    def rightSideView(self, root):
        res = []
        self.levelorder(root, 0, res)
        if res == []:
            return res
        val = []
        for elem in res:
            val.append(elem[-1])
        return val
            
            
            
            

   1            <---
 /   \
2     3         <---
 \     \
  5     4       <---

You should return [1, 3, 4].

This problem can be solved with level order travesal and store the more right element value every time.

This will take O(N) time and O(n) space.