leetcode Invert Binary Tree

 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         TreeNode* temp;
14         if(root==NULL) return root;
15         if(root->left==NULL&&root->right==NULL) return root;
16         else{
17         temp=root->left;
18         root->left=invertTree(root->right);
19         root->right=invertTree(temp);
20         }
21         
22         
23     }
24 };