LeetCode Invert Binary Tree

Invert a binary tree.

     4

   /   \

  2     7

 / \   / \

1   3 6   9

to

     4

   /   \

  7     2

 / \   / \

9   6 3   1

/**

 * Definition for a binary tree node.

 * struct TreeNode {

 *     int val;

 *     TreeNode *left;

 *     TreeNode *right;

 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}

 * };

 */

class Solution {

public:

    TreeNode* invertTree(TreeNode* root) {

        if (root == NULL) {

            return NULL;

        }

        

        TreeNode* n = root->left;

        root->left = root->right;

        root->right= n;

        

        invertTree(root->left);

        invertTree(root->right);

        

        return root;

    }

};

不知道想干什么，比镜像那题简单不少