Closest Binary Search Tree Value

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.

You are guaranteed to have only one unique value in the BST that is closest to the target.

Tips:

注意BST的性质，递归来做。

Code:

public class Solution {
    public int closestValue(TreeNode root, double target) {
        int a = root.val;
        TreeNode kid = target < a ? root.left : root.right;
        if (kid == null) return a;
        int b = closestValue(kid, target);
        return Math.abs(a - target) < Math.abs(b - target) ? a : b;
    }
}