Challenges

  • + 0 comments

    Could you explain the final section of your code:

    cn not in 
    (select count(c2.challenge_id) from challenges as c2 
     group by c2.hacker_id having
     c.hacker_id != c2.hacker_id)
    

    It seems to me as if it's checking that the count of challenges is NOT in the set of 'unique' hackers.