剑指 Offer 27. 二叉树的镜像

请完成一个函数，输入一个二叉树，该函数输出它的镜像。

例如输入：

镜像输出：

示例 1：

输入：root = [4,2,7,1,3,6,9]
输出：[4,7,2,9,6,3,1]

限制：

• 0 <= 节点个数 <= 1000

Python 解答：

1. 惯性思维想错了，不用这样复杂

   
   # Definition for a binary tree node.
   # class TreeNode:
   #     def __init__(self, x):
   #         self.val = x
   #         self.left = None
   #         self.right = None

class Solution:
def mirrorTree(self, root: TreeNode) -> TreeNode:
if not root:
return None
elif root.left == None and root.right == None:
return root
else:
node = TreeNode(root.val)
if root.left:
node.right = TreeNode(root.left.val)
node.right.left = self.mirrorTree(root.left.right)
node.right.right = self.mirrorTree(root.left.left)
if root.right:
node.left = TreeNode(root.right.val)
node.left.left = self.mirrorTree(root.right.right)
node.left.right = self.mirrorTree(root.right.left)
return node