Problem

Given a non-empty binary search tree and a target value, find the value in the BST that is closest to the target.

Note:

Given target value is a floating point.

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

Solution

class Solution {    public int closestValue(TreeNode root, double target) {        if (root == null) return -1;        int res = root.val;        while (root != null) {            if (Math.abs(root.val-target) < Math.abs(res-target)) res = root.val;            if (root.val > target) root = root.left;            else root = root.right;        }        return res;    }}