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原题链接在这里：https://leetcode.com/problems/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:
target 一定在找的path 上，若是出现了比minDiff 还小的 差值，就把改点更新为cloest.
但注意target 是 double, 会有溢出情况，所以minDiff 初始化成Double.MAX_VALUE.
Time Complexity: O(h). h 是树的高度。Space: O(1).
AC Java:
1 /** 2 * Definition for a binary tree node. 3 * public class TreeNode { 4 * int val; 5 * TreeNode left; 6 * TreeNode right; 7 * TreeNode(int x) { val = x; } 8 * } 9 */ 10 public class Solution { 11 public int closestValue(TreeNode root, double target) { 12 if(root == null){ 13 return -1; 14 } 15 16 int cloest = root.val; 17 double minDiff = Double.MAX_VALUE; 18 19 while(root != null){ 20 if(Math.abs(root.val - target) < minDiff){ 21 minDiff = Math.abs(root.val - target); 22 cloest = root.val; 23 } 24 if(target > root.val){ 25 root = root.right; 26 }else if(target < root.val){ 27 root = root.left; 28 }else{ 29 return root.val; 30 } 31 } 32 return cloest; 33 } 34 }
跟上Closest Binary Search Tree Value II
LeetCode Closest Binary Search Tree Value
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原文地址：http://www.cnblogs.com/Dylan-Java-NYC/p/5204357.html
