Closest Binary Search Tree Value

Given the root of a binary search tree and a target value, return the value in the BST that is closest to the target. If there are multiple answers, print the smallest.

Example 1:

Input: root = [4,2,5,1,3], target = 3.714286

Output: 4

Example 2:

Input: root = [1], target = 4.428571

Output: 1

Constraints:

• The number of nodes in the tree is in the range [1, 10⁴].
• 0 <= Node.val <= 10⁹
• -10⁹ <= target <= 10⁹