/**

  * Definition for a binary tree node.

  * struct TreeNode {

  *     int val;

  *     struct TreeNode *left;

  *     struct TreeNode *right;

  * };

  */

 struct TreeNode* invertTree(struct TreeNode* root){

     if(root==NULL)return root;

     struct TreeNode *r=(struct TreeNode*)malloc(sizeof(struct TreeNode));

     r->val=root->val;

     if(root->left!=NULL)r->right=invertTree(root->left);

     else r->right=NULL;

     if(root->right!=NULL)r->left=invertTree(root->right);

     else r->left=NULL;

     return r;

 }