【树】226. 翻转二叉树

 1 /**
 2  * Definition for a binary tree node.
 3  * struct TreeNode {
 4  *     int val;
 5  *     TreeNode *left;
 6  *     TreeNode *right;
 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 8  * };
 9  */
10 class Solution {
11 public:
12     TreeNode* invertTree(TreeNode* root) 
13     {
14         if (NULL == root) 
15         {
16             return root;
17         }
18         TreeNode *right = invertTree(root->right);
19         TreeNode *left = invertTree(root->left);
20         root->left = right;
21         root->right = left;
22         return root;
23 
24     }
25 };