题解 | #二叉树的中序遍历#

# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
#
# Dont try to understand it graphically, it is purely order of the code!!!
class Solution:
    def inorderTraversal(self , root: TreeNode) -> List[int]:
        if not root:
            return []
        res = []
        def dfs(node:TreeNode):
            if node.left:
                dfs(node.left)
            res.append(node.val)
            if node.right:
                dfs(node.right)
        dfs(root)
        return res