You are given the root
of a binary search tree (BST) and an integer val.
Find the node in the BST that the node's value equals val
and return the subtree rooted with that node. If such a node does not exist, return null
.
Input: root = [4,2,7,1,3], val = 2
Output: [2,1,3]
Input: root = [4,2,7,1,3], val = 5
Output: []