LeetCode 669. Trim a Binary Search Tree in Java

In this post we will solve the LeetCode 669 Trim a Binary Search Tree problem. This problem is ranked a Medium by LeetCode. It took me some extra time to figure out what I had to do.

Given the root of a binary search tree and the lowest and highest boundaries as low and high, 
trim the tree so that all its elements lies in [low, high]. 
Trimming the tree should not change the relative structure of the elements that will remain in the tree 
(i.e., any node's descendant should remain a descendant).
It can be proven that there is a unique answer.

Return the root of the trimmed binary search tree. 
Note that the root may change depending on the given bounds.


o The number of nodes in the tree in the range [1, 10^4].
o 0 <= Node.val <= 10^4
o The value of each node in the tree is unique.
o root is guaranteed to be a valid binary search tree.
o 0 <= low <= high <= 10^4

Related Topics:

o Tree
o Depth-First Search
o Binary Search Tree
o Binary Tree

The problem clearly states that we are presented with a binary search tree which specifies the relationship between node values. Continue reading “LeetCode 669. Trim a Binary Search Tree in Java”