Here is a variation of the problem that asks for two values that add up to an expected value

Given the root of a binary search tree, and a target K, return two nodes in the tree whose sum equals K.

# Understanding the Problem

This is very similar to any problem that requires us to find two values that add up to a number. We simply need to keep track of all the numbers we have seen and simultaneously check to see if a number exists that satisfies our condition

# Optimizing

Since this is a Binary Search Tree, we can optimize the search by only traversing certain branches of the tree.

# Solving it

- Traverse the tree
- Build a set containing the values we have seen
- On each node, check if the "inverse" ie. (
**sum - value**) exists in our set. - If it does then the current value and the inverse is our solution