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_values = [] in_values = [] post_values =[] # 先序遍历 def pre_order(node): if node is None: return None

        pre_values.append(node.val)
        pre_order(node.left)
        pre_order(node.right)
        return pre_values
    
    # 中序遍历
    def in_order(node):
        if node is None:
            return None
        
        in_order(node.left)
        in_values.append(node.val)
        in_order(node.right)
        return in_values
    
    # 后序遍历
    def post_order(node):
        if node is None:
            return None
        
        post_order(node.left)
        post_order(node.right)
        post_values.append(node.val)
        return post_values
    res = []
    res.append(pre_order(root))
    res.append(in_order(root))
    res.append(post_order(root))
    return res