AlgoDaily - Two Sum from BST

Two Sum from BST (Hard)

Good morning! Here's our prompt for today.

You may see this problem at Netflix, Spotify, Visa, Auth0, Grammarly, Weave, Bosch Global, Akamai, Pagerduty, Cornerstone, and Zuora.

This problem is a fun combination of the famous Two Sum problem combined with a binary search tree. Given the root of a binary search tree, and a target integer K, return true if there exist two nodes in the said tree whose sum equals K. If no pair fits this match, return false.

Say we are given this tree:

JAVASCRIPT

1/***
2
3  Input:
4    5    
5   / \     
6  3   8
7 /        
81
9
10***/

Each node is defined in the following manner:

JAVASCRIPT

1class Node {
2	constructor(val) {
3		this.value = val;
4		this.left = null;
5		this.right = null;
6	}
7}

And thus the below setup and execution code should hold true:

JAVASCRIPT

1const root = new Node(5);
2root.left = new Node(3);
3root.right = new Node(8);
4root.left.left = new Node(1);
5
6const target = 11;
7
8twoSumFromBST(root, target);
9// true because 3 + 8 = 11

Constraints

Number of vertices in the tree <= 100000
The values in the vertices will be between -100000 and 1000000
The target value will be between -100000 and 100000
Expected time complexity : O(n)
Expected space complexity : O(n)

xxxxxxxxxx
​
 
var assert = require('assert');
​
function inOrder(root) {}
​
function twoSumFromBST(root, target) {
  // Fill in this method
  return root;
}
​
class Node {
  constructor(val) {
    this.value = val;
    this.left = null;
    this.right = null;
  }
}
​
function Node(val) {
  this.val = val;
  this.left = null;
  this.right = null;
}
​
// Regular binary trees
var tree1 = new Node(4);
tree1.left = new Node(1);
tree1.right = new Node(3);

OUTPUT

Results will appear here.