1008. Construct Binary Search Tree from Preorder Traversal

void Insert(TreeNode *& root,int data)
    {
        if(root==nullptr)
        {
            root = new TreeNode(data); 
        }else
        {
            if(data<root->val)
            {
                Insert(root->left,data);
            }else if(data>root->val)
            {
                Insert(root->right,data);
            }
        }
    }
    TreeNode* bstFromPreorder(vector<int>& preorder) {
        TreeNode * root = nullptr;
        for(int i=0 ; i<preorder.size(); i++)
        {
            Insert(root,preorder[i]);
        }
        return root;
    }