/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* struct TreeNode *left;
* struct TreeNode *right;
* };
*/
struct TreeNode* invertTree(struct TreeNode* root) {
if(!root)
return NULL;
if(!root->left && !root->right)
return root;
struct TreeNode *temp = root->left;
root->left = root->right;
root->right = temp;
if(root->left)
root->left = invertTree(root->left);
if(root->right)
root->right =invertTree(root->right);
return root;
}