Find the closest element in Binary Search Tree

Given a binary search tree and a target node K. The task is to find the node with minimum absolute difference with given target value K.


// For above binary search tree
Input  :  k = 4
Output :  4

Input  :  k = 18
Output :  17

Input  :  k = 12
Output :  9

A simple solution for this problem is to store Inorder traversal of given binary search tree in an auxiliary array and then by taking absolute difference of each element find the node having minimum absolute difference with given target value K in linear time.

An efficient solution for this problem is to take advantage of characteristics of BST. Here is the algorithm to solve this problem :


Time complexity : O(h) where h is height of given Binary Search Tree.

Reference :

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