94.binary-tree-inorder-traversal.py

#
# @lc app=leetcode id=94 lang=python3
#
# [94] Binary Tree Inorder Traversal
#

# @lc code=start
# 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 inorderTraversal(self, root: TreeNode) -> List[int]:
        res = [] 
        self.helper(root, res) 
        return res 
    
    def helper(self, root: TreeNode, res: List[int]) -> None:
        if root: 
            self.helper(root.left, res)
            res.append(root.val)
            self.helper(root.right, res)

# @lc code=end