Find the node with the given value in a binary search tree. If the node is not found, return null.
Example 1
Input: root = [4,2,7,1,3], val = 5
Output: null
Explanation: The value 5 is not in the tree.
Output: null
Explanation: The value 5 is not in the tree.
Example 2
Input: root = [4,2,7,1,3], val = 2
Output: [2,1,3]
Explanation: The subtree rooted at 2.
Output: [2,1,3]
Explanation: The subtree rooted at 2.