题解 | #二叉树的后序遍历#

class Solution:
    def postorderTraversal(self , root: TreeNode) -> List[int]:
        # write code here
        res = []
        if root is not None:
            if root.left is not None:
                res += self.postorderTraversal(root.left)
            if root.right is not None:
                res += self.postorderTraversal(root.right)
            res += [root.val]
        return res