Leetcode 270. Closest Binary Search Tree Value

最新推荐文章于 2022-11-10 13:30:08 发布

转载最新推荐文章于 2022-11-10 13:30:08 发布 · 76 阅读

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原文链接：http://www.cnblogs.com/lettuan/p/6247221.html

本文介绍了一种方法来解决二叉搜索树中寻找最接近给定目标值的问题。通过递归遍历树结构，并比较当前节点与目标值的距离，可以有效地找到最接近的目标值。文章提供了一个具体的Python实现案例。

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.

沿着root向下找即可，每次判段一下是在root左边还是右边。注意没有child的情况。

 1 # Definition for a binary tree node.
 2 # class TreeNode(object):
 3 #     def __init__(self, x):
 4 #         self.val = x
 5 #         self.left = None
 6 #         self.right = None
 7 
 8 class Solution(object):
 9     def closestValue(self, root, target):
10         """
11         :type root: TreeNode
12         :type target: float
13         :rtype: int
14         """
15         #if target == root.val:
16         #    return root.val
17         
18         if target < root.val:
19             if not root.left:
20                 return root.val
21             else:
22                 c1 = self.closestValue(root.left, target)
23                 if abs(c1 - target) < abs(root.val - target):
24                     return c1
25                 else:
26                     return root.val
27         else:
28             if not root.right:
29                 return root.val
30             else:
31                 c2 = self.closestValue(root.right, target)
32                 if abs(c2 - target) < abs(root.val - target):
33                     return c2
34                 else:
35                     return root.val