94. Binary Tree Inorder Traversal
用 root.left and root.right
来判断逻辑有点太麻烦了
直接在进入处理逻辑之前判断当前节点是否为空就行。为空就不继续。
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 inorderTraversal(self, root: Optional[TreeNode]) -> List[int]:
ans = []
def dfs(root):
if not root:
return
dfs(root.left)
ans.append(root.val)
dfs(root.right)
dfs(root)
return ans