## December 2015 Contest -- Final Results

This was our first contest of the 2015-2016 season. A total of 3784 users logged into the contest during its 4-day span. Of those, 2835 participants submitted at least one solution, hailing from 73 different countries:

 1033 USA  244 CHN  241 VNM  117 IRN   99 ROU   85 CAN   63 BRA
62 IND   52 BLR   47 GEO   43 RUS   43 AUS   36 FRA   33 KAZ
31 IDN   29 BGR   28 BGD   26 THA   26 DEU   25 EGY   24 HRV
23 POL   22 SGP   22 ITA   22 CUB   21 SYR   21 ARM   19 TKM
19 JPN   19 AZE   16 KOR   13 GRC   12 GBR   12 EST   11 TWN
11 TUR   11 NLD   11 HKG   11 FIN   10 MKD   10 MEX   10 ARG
9 ZAF    8 UKR    8 NZL    7 PRT    7 ISR    7 COL    6 SRB
6 BEL    5 MYS    5 LTU    5 CZE    4 VEN    4 UZB    4 MDA
4 HUN    4 DOM    4 BIH    3 AUT    2 TUN    2 TJK    2 SVN
2 PER    2 LVA    2 KGZ    2 IRL    2 CYP    2 CHL    1 SWE
1 MNG    1 LUX    1 LBN


The average participant who submitted code submitted solutions for 2.7 problems. In total, there were 7533 graded submissions, broken down by language as follows:

 2700 C++
2624 C++11
1486 Java
326 Pascal
145 Python 2.7.6
130 Python 3.4.0
76 C


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 2015 December Contest, Platinum

The platinum division had 392 total participants, of whom 231 were pre-college students -- this alone was quite impressive given that at the beginning of the contest, only about 2 dozen participants started out in the platinum division; the rest arrived via in-contest promotion from the gold division. We saw quite a few high scores in the platinum division this time around, indicating that we have a highly competitive season ahead of us! Full results are here. Congratulations to all of the top participants for their excellent results!

# 1

Max Flow
View problem  |   Test data   |   Solution

# 2

High Card Low Card (Platinum)
View problem  |   Test data   |   Solution

# 3

Counting Haybales
View problem  |   Test data   |   Solution

## USACO 2015 December Contest, Gold

The Gold division had 1020 total participants, of whom 637 were pre-college students. We had a very large number of perfect scores in gold (and in bronze and silver as well), as is typical for the first contest of the season, with advanced students being promoted in-contest to higher divisions.

All competitors who scored 800 or higher on this contest are automatically promoted to the platinum division -- congratulations to you all! Detailed results for those promoted are here.

# 1

High Card Low Card (Gold)
View problem  |   Test data   |   Solution

# 2

Fruit Feast
View problem  |   Test data   |   Solution

# 3

Bessie's Dream
View problem  |   Test data   |   Solution

## USACO 2015 December Contest, Silver

The Silver division had 1423 total participants, of whom 1042 were pre-college students. Scores in the silver division had a reasonable distribution, with a large number of perfect scores.

All competitors who scored 750 or higher on this contest are automatically promoted to the gold division. Detailed results for those promoted are here.

# 1

Switching on the Lights
View problem  |   Test data   |   Solution

# 2

High Card Wins
View problem  |   Test data   |   Solution

# 3

Breed Counting
View problem  |   Test data   |   Solution

## USACO 2015 December Contest, Bronze

The Bronze division had 2830 total participants, of whom 2201 were pre-college students.

All competitors who scored 750 or higher on this contest are automatically promoted to the silver division -- to all who were promoted, congratulations! Detailed results for those promoted are here.

# 1

Fence Painting
View problem  |   Test data   |   Solution

# 2

Speeding Ticket
View problem  |   Test data   |   Solution

# 3

Contaminated Milk
View problem  |   Test data   |   Solution

## Final Remarks

The 2015-2016 season is off to a great start! This contest set new records for participation, and aside from a short network outage late Monday evening, it ran completely smoothly. The most notable aspect of this contest, of course, is our newly recalibrated divisions, with bronze, silver, and gold becoming slightly easier than before, and with the addition of a new "platinum" division that is intended to be roughly on par with the high end of the older gold division. I am optimistic that the new division structure will make it easier for new students start in the bronze division, and also easier for promoted students to get a foothold in their new divisions. Based on the results of this contest, I believe we are indeed starting to achieve these goals. Hundreds of participants succeeded in moving up to higher divisions either through in-contest or after-contest promotions. I expect the remaining contests in this season to have quite a few less perfect scores, now that everyone is settled in an appropriate initial division. It looks like we may need to tune the difficulty of the platinum division to be perhaps one notch higher as well, in order to provide more separation at the very top of the curve.

For those still waiting to achieve promotion, remember that 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. Remember that the more practice you get, the better your algorithmic coding skills will become! To help you fix any bugs in your code, you are encouraged to consult the official solutions above and to make use of "analysis mode" to re-submit improved versions of your solutions.

A large number of people contribute towards the quality and success of USACO contests. Those who helped with this contest include Mark Gordon, Richard Peng, Nathan Pinsker, Austin Bannister, Austin Anderson, Allen Chen, Aayush Gupta, Jonathan Paulson, and Nick (Huaiyu) Wu. Thanks also to Amy Quispe for helping to maintain our social media presence (Facebook: https://www.facebook.com/UsacoContests, Twitter: (https://twitter.com/UsacoContests), our translators for allowing us to offer this contest in five additional languages, to Clemson CCIT for providing our main contest server, and to our sponsors for their generous support: Usenix, Dropbox, and D.E. Shaw.

Happy coding!

- Brian Dean (bcdean@clemson.edu)