Hi, I've tried C++ recursive solution but it seems a lot fast solution(13-16ms) has using the following statement to return result rather than explicit new one, I'm wondering if this will change the original tree so it's not a good answer in real life?

```
root->left = trimBST(root->right, L, R);
root->right =trimBST(root->right, L, R);
return root;
Thanks,
```