lowestCommonAncestor = function(root, p, q) {
    const isGreater = (p.val < root.val) && (q.val < root.val);
    if (isGreater) return lowestCommonAncestor(root.left, p, q);

    const isLess = (root.val < p.val) && (root.val < q.val);
    if (isLess) return lowestCommonAncestor(root.right, p, q);

    return root;
}
https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree/
Time O(H) | Space O(H)
@param {TreeNode} root
@param {TreeNode} p
@param {TreeNode} q
@return {TreeNode}