Given a non-empty binary search tree and a target value, find k values in the BST that are closest to the target.
Note:
- Given target value is a floating point.
- You may assume k is always valid, that is: k ≤ total nodes.
- You are guaranteed to have only one unique set of k values in the BST that are closest to the target.
Example:
Input: root = [4,2,5,1,3], target = 3.714286, and k = 2
4
/ \
2 5
/ \
1 3
Output: [4,3]
Follow up:
Assume that the BST is balanced, could you solve it in less than O(n) runtime (where n = total nodes)?