2020 December Contest Contest -- Final Results

The 2020 December Contest contest featured algorithmic programming problems covering a wide range of techniques and levels of difficulty. A total of 10752 distinct users logged into the contest during its 4-day span. A total of 9508 participants submitted at least one solution, hailing from 80 different countries:

 5297 USA 2412 CHN  362 CAN  291 KOR  131 IND   96 VNM   93 ROU
   85 MYS   61 GEO   42 POL   38 TWN   37 SGP   33 FRA   32 RUS
   31 IRN   28 BLR   25 BGD   25 AUS   22 MEX   22 HKG   21 GBR
   19 ARM   18 UKR   18 KAZ   16 SLV   16 JPN   15 TUR   15 MNG
   15 DEU   12 ITA   10 IDN    9 AZE    8 HRV    8 GRC    7 SAU
    7 EST    7 COL    7 BGR    6 TJK    6 THA    6 NGA    6 CUB
    6 BRA    5 TKM    5 ESP    4 VEN    4 PHL    4 NZL    4 MDA
    4 LTU    4 KGZ    4 ISR    4 EGY    3 SRB    3 NLD    3 CHE
    3 BHS    3 BEL    2 TUN    2 SYR    2 SVN    2 SVK    2 PRK
    2 LUX    2 FIN    2 ARG    1 ZAF    1 SOM    1 SJM    1 PRT
    1 MMR    1 LKA    1 IRL    1 HUN    1 CMR    1 BRN    1 BIH
    1 BHR    1 ATA    1 ARE
In total, there were 27387 graded submissions, broken down by language as follows:

 9131 C++11
 7703 Java
 5841 C++
 4452 Python 3.4.0
  132 Python 2.7.6
  120 C
    8 Pascal

Below are the detailed results for each of the platinum, gold, silver, and bronze contests. You will also find solutions and test data for each problem, and by clicking on any problem you can practice re-submitting solutions in "analysis mode". If you are logged in, you will also see your own specific results below alongside the contest(s) you took.

USACO 2020 December Contest, Platinum

The platinum division had 393 total participants, of whom 253 were pre-college students. The contest proved to be quite challenging, with only a small number of perfect scores. Results for top scorers are here. Congratulations to all of the top participants for their excellent results!

1

Sleeping Cows
View problem  |   Test data   |   Solution

2

Spaceship
View problem  |   Test data   |   Solution

3

Cowmistry
View problem  |   Test data   |   Solution

USACO 2020 December Contest, Gold

The gold division had 945 total participants, of whom 675 were pre-college students. The gold division problems were particularly difficult this time around, so our promotion cutoff is set a bit lower than usual to compensate --- all competitors who scored 600 or higher on this contest are automatically promoted to the platinum division. Detailed results for all those promoted are here.

1

Replication
View problem  |   Test data   |   Solution

2

Bovine Genetics
View problem  |   Test data   |   Solution

3

Square Pasture
View problem  |   Test data   |   Solution

USACO 2020 December Contest, Silver

The silver division had 3263 total participants, of whom 2538 were pre-college students. All competitors who scored 800 or higher on this contest (185 of them, from the USA) are automatically promoted to the gold division.

1

Cowntagion
View problem  |   Test data   |   Solution

2

Rectangular Pasture
View problem  |   Test data   |   Solution

3

Stuck in a Rut
View problem  |   Test data   |   Solution

USACO 2020 December Contest, Bronze

The bronze division had 7858 total participants, of whom 6127 were pre-college students. All competitors who scored 800 or higher on this contest (1312 of them, from the USA) are automatically promoted to the silver division.

1

Do You Know Your ABCs?
View problem  |   Test data   |   Solution

2

Daisy Chains
View problem  |   Test data   |   Solution

3

Stuck in a Rut
View problem  |   Test data   |   Solution

Final Remarks

Wow! Participation in this contest showed huge increases from last year -- nearly 40 percent, finally bringing us to the elusive "10K" number of participants we have been striving to achieve now for many years. I'm thrilled to see such high levels of enthusiasm for algorithmic computer science, and equally thrilled that the contest went smoothly with no technical issues (at one point we have 900+ simultaneous users!). Due to popular demand, we've finally switched away from file input/output, which seems to be going over well. In terms of difficulty, all four divisions contained some rather challenging problems --- perhaps gold being the most challenging this time around in relative terms. However, we still saw a large number of high scores and large numbers of promotions. Remember that promotion cutoffs are intentionally set so that participants being promoted will be adequately well-prepared for the next-highest division.

For those not yet promoted, remember that the more practice you get, the better your algorithmic coding skills will become -- please keep at it! USACO contests are designed to challenge even the very best students, and it can take a good deal of hard work to excel at them. To help you fix any bugs in your code, you can now re-submit your solutions and get feedback from the judging server using "analysis mode". There will be many more opportunities for promotion on future contests as you continue to practice and improve your skills.

A large number of people contribute towards the quality and success of USACO contests. Those who helped with this contest include Benjamin Qi, Danny Mittal, Walden Yan, Nick Wu, Spencer Compton, Riya Arora, and Dhruv Rohatgi. A special shout-out to Benjamin Qi, for his careful attention to detail in crafting many of our challenging platinum problems (to give you an idea of how much work he put into these, he benchmarked 21 different solution approaches for one of the platinum problems!). Thanks also to our translators and to Clemson CCIT for providing our contest infrastructure. Finally, we are grateful to the USACO sponsors for their generous support: TwoSigma, D.E. Shaw, and Ansatz Trading.

We look forward to seeing everyone again in 2021 for our January contest!

Happy coding!

- Brian Dean ([email protected])
Professor and Chair, Division of Computer Science, School of Computing, Clemson University
Director, USACO