236.二叉树的最近公共祖先

var lowestCommonAncestor = function (root, p, q) {
  if (root === null || root === p || root === q) {
    return root;
  }
  let p1 = lowestCommonAncestor(root.left, p, q);
  let p2 = lowestCommonAncestor(root.right, p, q);
  if (p1 && p2) {
    return root;
  } else {
    return p1 || p2;
  }
};