So it’s confirmed, I’m qualified for round 1.

In case you missed them, here are my write-ups for the qualifier problems:

• Reversort
• Moons and Umbrellas
• Reversort Engineering (it’s the same as for Reversort)
• Median Sort
• Cheating Detection

The problems were fun and interesting, on the whole. I do regret a few things.

1. It’s really a lot of sorting for a single round.
2. (related) It’s a lot of abstract computer science for a qualifier.
3. My initial solution to E-large fell in the bad luck territory of the test set. For no good reason. It’s a pity it had so few tests. And I say that as someone who didn’t really attempt it during the challenge. There are probably quite a few poor souls who paid a higher price for it.

On the positive side: they’re now providing the actual test sets in the analyses! That’s the first great news you’re hearing from me since they revamped the platform, take heed!

Here’s my writing prompts list, for later perusal.

• The analysis says Reversort is feasible in O(NlgN). That might be interesting.
• As mentioned in the post for Median Sort, there are at least two other fun classes of ways to solve:
  • an optimal algorithm (non-asymptotically) for the small set
  • mergesort and heapsort for the medium set
  • ternary quicksort for the large set