const lowestCommonAncestor = function (root, p, q) {
  if (!root || root === p || root === q) {
    return root
  }
  const left = lowestCommonAncestor(root.left, p, q);
  const right = lowestCommonAncestor(root.right, p, q);
  return !left ? right : (!right ? left : root);
};