Locate a Subtree by Its Search Key

### Problem Given the root pointer of a binary search tree and val, return the existing node whose value equals val, including its entire subtree. Return nullptr when no matching node exists. TreeNode is the original node type; level-order lists below only describe trees. ```cpp class Solution { public: TreeNode* searchBST(TreeNode* root, int val); }; ``` ### Examples **Example 1:** ```text root = [8,4,11,2,6], val = 4 Output subtree: [4,2,6] Explanation: Return the original node holding 4. ``` **Example 2:** ```text root = [8,4,11,2,6], val = 7 Output: nullptr Explanation: No node has value 7. ``` ### Constraints - The BST contains 1 through 5000 nodes. - Both node values and val are in [1,10000000]. - The given tree satisfies the binary-search ordering. ### Contract considerations Preserve the TreeNode pointer input and subtree result. ```hint Read the boundary condition Which subtree can still contain the desired key? ``` ### Boundary reminders Preserve the TreeNode pointer input and subtree result.