Lowest-common-ancestor-of-BST.js

/*
Given a binary search tree (BST), find the lowest common ancestor (LCA) node of two given nodes in the BST.

According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes p and q as the lowest node in T that has both p and q as descendants (where we allow a node to be a descendant of itself).”

 

Example 1:

Input: root = [6,2,8,0,4,7,9,null,null,3,5], p = 2, q = 8
Output: 6
Explanation: The LCA of nodes 2 and 8 is 6.

Example 2:

Input: root = [6,2,8,0,4,7,9,null,null,3,5], p = 2, q = 4
Output: 2
Explanation: The LCA of nodes 2 and 4 is 2, since a node can be a descendant of itself according to the LCA definition.

Example 3:

Input: root = [2,1], p = 2, q = 1
Output: 2


*/

var lowestCommonAncestor = function (root, p, q) {
	let curr = root;

	while (curr) {
		if (curr.val < p.val && curr.val < q.val) {
			curr = curr.right;
		} else if (curr.val > p.val && curr.val > q.val) {
			curr = curr.left;
		} else {
			return curr;
		}
	}
};