Leetcode 270: 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.
 1 /**
 2  * Definition for a binary tree node.
 3  * public class TreeNode {
 4  *     public int val;
 5  *     public TreeNode left;
 6  *     public TreeNode right;
 7  *     public TreeNode(int x) { val = x; }
 8  * }
 9  */
10 public class Solution {
11     public int ClosestValue(TreeNode root, double target) {
12         var candidate = new int[] {Int32.MaxValue};
13         DFS(root, target, candidate);
14         return candidate[0];
15     }
16     
17     private void DFS(TreeNode node, double target, int[] candidate)
18     {
19         if (node == null) return;
20         
21         if (candidate[0] == Int32.MaxValue)
22         {
23             candidate[0] = node.val;
24         }
25         else
26         {
27             double d1 = Math.Abs((double)node.val - target); 
28             double d2 = Math.Abs((double)candidate[0] - target);
29             
30             if (d1 < d2)
31             {
32                 candidate[0] = node.val;
33             }
34         }
35         
36         if ((double)node.val > target)
37         {
38             DFS(node.left, target, candidate);
39         }
40         else
41         {
42             DFS(node.right, target, candidate);
43         }
44     }
45 }

 

posted @ 2017-12-20 03:23  逸朵  阅读(316)  评论(0)    收藏  举报