It was as follows:

• When I asked how I could be of service at LinkedIn, the interviewer could not answer the question, stating they were not sure whether I would be filling an entry-level role or a senior role.
• It was difficult to understand the interviewer’s accent.
• I was given the same question I was asked ten years ago: How do you test whether two binary trees are mirror images, for which the entry-level coder's answer would be something hideous like:

cpp bool isMirror(Node* tree1, Node* tree2) { bool ret_val = false; if(tree1 != null && tree2 != null) { ret_val = (tree1->m_data == tree2->m_data) && isMirror(tree1->m_lhs, tree2->m_rhs) && isMirror(tree1->m_rhs, tree2->m_lhs); } return (tree1 == null && tree2 == null) ? true : ret_val; }

• The interviewer did not want an iterative solution that avoided stack overflows and made better use of CPU cache, much less a PhD with physics and maths skills.

How do you apply quantum mechanics to data mining?

Sadly, the interviewer did not seem to know the answer to a very basic question. Even the most mediocre physics undergraduate could answer it in under five minutes.