1、递归-解释中序遍历的概念即先访问左子树中间访问该节点最后访问右子树# Definition for a binary tree node. # class TreeNode: # def __init__(self, val0, leftNone, rightNone): # self.val val # self.left left # self.right right class Solution: def inorderTraversal(self, root: Optional[TreeNode]) - List[int]: # 递归 # 中序遍历的含义先访问左子树中间访问自身最后访问右子树 ans [] def dfs(node): # 出口 if not node: return None dfs(node.left) ans.append(node.val) dfs(node.right) return None dfs(root) return ans