ツリーを反転-C++

class Solution {
public:
    /**
     * @param root: a TreeNode, the root of the binary tree
     * @return: nothing
     */
     void look(TreeNode *root)
     {
         if(root==NULL)
         return ;
         if(root->left==NULL&&root->right==NULL)
         return;
         TreeNode *x;
         x=new TreeNode;
         x=root->left;
         root->left=root->right;
         root->right=x;
         look(root->left);
         look(root->right);
     }
    void invertBinaryTree(TreeNode *root) {
        look(root);
        // write your code here
    }
};