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 = Noneclass 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.