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: OptionalTreeNode) -> Listint:
res = \[\]
def inorder(node):
if not node:
return
inorder(node.left)
res.append(node.val)
inorder(node.right)
inorder(root)
return res