LeetCode 226: Invert Binary Tree

/**
* 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) {
TreeNode *temp;
if(root){
temp = root->right;
root->right = root->left;
root->left = temp;
invertTree(root->left);
invertTree(root->right);
}
return root;

}
};