[leetcode]270. Closest Binary Search Tree Value二叉搜索树中找target的最接近值

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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.

Example:

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

    4
   / \
  2   5
 / \
1   3

Output: 4

题目

给定一棵二叉搜索树和一个target，求出其节点中最接近该target的值。

思路

1. based on the BST's attribution ( left < root < right), we use binary search

代码

 class Solution {
     public int closestValue(TreeNode root, double target) {
         int result = root.val;
         while(root != null){
             //update result if the current value is closer to target
             if(Math.abs(target - root.val) < Math.abs(target - result)){
                 result = root.val;
             }
             //binary search
             root = root.val > target? root.left: root.right;
         }
         return result;
     }
 }