226. Invert Binary Tree

Invert a binary tree.

Example:

Input:

4   /   \  2     7 / \   / \1   3 6   9复制代码

Output:

4   /   \  7     2 / \   / \9   6 3   1复制代码

Trivia: This problem was inspired by this original tweet by Max Howell:

Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so f*** off.

思路:递归 代码：python3

class Solution:    def invertTree(self, root: TreeNode) -> TreeNode:        if root:            root.left,root.right = self.invertTree(root.right),self.invertTree(root.left)            return root复制代码