LeetCode:Invert Binary Tree

Invert a binary tree.

     4   /   \  2     7 / \   / \1   3 6   9

to

     4   /   \  7     2 / \   / \9   6 3   1

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 fuck off.

这道题有一个梗,homebrew的作者去Google面试就被问了这道题，结果他想了半天 没 想 出 来！哈哈哈

class Solution {public:    TreeNode* invertTree(TreeNode* root) {        if(root==NULL||root->left==NULL&&root->right==NULL){            return root;        }        TreeNode* temp=root->left;        root->left=root->right;        root->right=temp;        if(root->left){            invertTree(root->left);        }        if(root->right){            invertTree(root->right);        }        return root;    }};