Recursively call the **sortedArrayToBST()** method providing new vector for each call to construct left and right children:

```
class Solution {
public:
TreeNode *sortedArrayToBST(vector<int> &num) {
if(num.size() == 0) return NULL;
if(num.size() == 1)
{
return new TreeNode(num[0]);
}
int middle = num.size()/2;
TreeNode* root = new TreeNode(num[middle]);
vector<int> leftInts(num.begin(), num.begin()+middle);
vector<int> rightInts(num.begin()+middle+1, num.end());
root->left = sortedArrayToBST(leftInts);
root->right = sortedArrayToBST(rightInts);
return root;
}
};
```