Mercor Software Engineer Interview Experience — No-Coding Technical Screen with Code-Reading Questions, Did Not Pass

I applied online. There is no recruiter screen - first call is a HM screen where they ask you basic questions.

Next screen is a 30 minute technical screen with no coding. Mine had 4 questions -

1. Tell me the worst sorting algorithm - (n!) and explain how you would calculate each permutation

2. You visit two coffeeshops A and B and order 2 drinks from each. Each drink gets a quality score. What is the probability that both drinks from A have higher scores than both drinks from B?

I thought this was a dumb question but the answer is 1/6

AABB, ABAB, BBAA, ABBA, BAAB, BABA

3. Code read - ask for what improvements I would make

public String buildCsv(List<List<String>> rows) {
String s = "";
for (List<String> row : rows) {
for (String cell : row) {
s += cell + ",";
}
s += "\n";
}
return s;
}

4. Code read - asked about client failing in the middle of the call

import java.util.Map;
public class PaymentService {
private final PaymentProvider provider;
private final Database db;
public Map<String, String> createPayment(String userId, int amountCents) {
// calls external provider (e.g., Stripe-like)
String chargeId = provider.charge(userId, amountCents);
db.insert("payments", Map.of(
"user_id", userId,
"amount", amountCents,
"charge_id", chargeId
));
return Map.of("status", "ok", "charge_id", chargeId);
}
}

Ultimately, I did not pass.