# class TreeNode: # def __init__(self, x): # self.val = x # self.left = None # self.right = None # # 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可 # # # @param root TreeNode类 the root of binary tree # @return int整型二维数组 # class Solution: def threeOrders(self, root: TreeNode) -> List[List[int]]: # write code here pre_list = [] in_list = [] post_list = [] def preorder(leaf: TreeNode): if not leaf: return pre_list.append(leaf.val) preorder(leaf.left) preorder(leaf.right) def inorder(leaf: TreeNode): if not leaf: return inorder(leaf.left) in_list.append(leaf.val) inorder(leaf.right) def postorder(leaf: TreeNode): if not leaf: return postorder(leaf.left) postorder(leaf.right) post_list.append(leaf.val) preorder(root) inorder(root) postorder(root) result = [] result.append(pre_list) result.append(in_list) result.append(post_list) return result