Like the commenter above specified, the best way to satisfy the grader is to get the answer key, regardless of how clever you are, especially when you realize lots of these benchmarks have flaws (i.e wrong answers, overly restrictive grading etc).
Anyway, if you read TFA, you'd see that HF did actually have the answers: "While the intrusion did reach Hugging Face's internal infrastructure, the only customer content accessed was the set of ExploitGym/CyberGym challenge solutions stored in five datasets."