USACO December 2014 Contest -- Final Results

This was the first contest of our 2014-2015 contest season. A total of 2614 participants submitted at least one solution, hailing from 75 different countries:

 1294 USA  173 CHN   97 CAN   80 VNM   74 IRN   72 BLR
61 GEO   51 IND   40 KAZ   35 TUR   33 BGD   32 RUS
29 BGR   26 DEU   25 IDN   24 ROU   23 ARM   22 MEX
20 VEN   20 FRA   19 SGP   18 POL   18 EGY   17 KOR
16 HRV   15 GRC   14 UKR   13 TKM   13 SYR   13 SWE
12 CUB   12 BRA   11 TJK   11 JPN   11 ISR   11 GBR
11 EST   11 AUS   10 ZAF   10 ITA    8 COL    7 TWN
7 HUN    7 BIH    6 MYS    5 MKD    5 LTU    5 IRL
5 FIN    4 ZWE    4 PRT    4 NZL    4 MNG    4 KGZ
4 DOM    4 AZE    3 SRB    3 NLD    3 AUT    3 ARG
2 NGA    2 CZE    2 CYP    2 BEL    2 ALB    1 WSM
1 ESP    1 TUN    1 THA    1 SVK    1 PRI    1 PHL
1 MDA    1 LUX    1 HKG    2 ???


In total, there were 6619 graded submissions, broken down by language as follows:

 2956 C++
1912 Java
982 C++11
234 Pascal
196 Python 2.7.6
153 Python 3.4.0
143 C


Below are the detailed results for each of the 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 you took.

USACO 2014 December Contest, Gold

The gold division had 329 total participants, of whom 248 were pre-college students. We saw a very impressive set of results on this contest, with 86 perfect scores! -- congratulations to those participants and all others who turned in strong results on this contest. Discounting the perfect scores, the overall score histogram for the gold contest was relatively flat, with scores ranging somewhat uniformly from 0 through 1000:

Detailed results for all gold participants are here.

1

Guard Mark
View problem  |   Test data   |   Solution

2

Marathon
View problem  |   Test data   |   Solution

3

Cow Jog
View problem  |   Test data   |   Solution

USACO 2014 December Contest, Silver

The silver division had 343 total participants, of whom 284 were pre-college students. The score distribution for silver also shows a large spike at 1000, being otherwise fairly uniform:

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

1

Piggyback
View problem  |   Test data   |   Solution

2

Marathon
View problem  |   Test data   |   Solution

3

Cow Jog
View problem  |   Test data   |   Solution

USACO 2014 December Contest, Bronze

The bronze division had 1942 total participants, of whom 1609 were pre-college students. The overall score distribution for bronze follows a similar pattern to that of gold and silver, although you can see distinct peaks representing those who solved 0, 1, 2, 3, and 4 problems respectively:

All competitors who scored 800 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

Marathon
View problem  |   Test data   |   Solution

2

Crosswords
View problem  |   Test data   |   Solution

3

Cow Jog
View problem  |   Test data   |   Solution

4

Learning by Example
View problem  |   Test data   |   Solution

Final Remarks

I'm quite happy with the results on this contest! We had record-setting participation, and a large number of promotions both to silver and to gold. There were quite a few more perfect scores in the gold division than we have seen on many past contests, and this was partly by design, as we are trying to keep the difficulty of the gold contest from getting too far out of hand (we may in the near future take additional steps to help differentiate the folks at the top of the gold division). Score distributions were quite reasonable, with scores generally spread across the board. The contest was extended by one extra day due to a typo -- I had accidentally written Dec 16 instead of Dec 15 in one place in the instructions, so to be fair we left the contest open one extra day.

The USACO staff has been hard at work in recent months on updates to our contest and training infrastructure. If you have taken our contests before, you probably noticed that starting with this contest, we are providing detailed feedback on every submission, both in order to help competitors avoid making silly errors, and also to make our grading more similar to the grading at the IOI. To support this, we are now running on a brand new "cloud"-based distributed grading system, capable of handling far more load than our previous setup. We are also showing full results in bronze and silver only for those promoted, instead of for all participants -- this change was made to prevent lower-scoring competitors from feeling in any way embarrased by a public listing of their results. In terms of training, our coaches have been collaborating for quite some time on enhancements to the USACO training pages, which we hope to be able to unveil before too long. The coaches have also set up a Facebook page (https://www.facebook.com/UsacoContests) and twitter account (https://twitter.com/UsacoContests) to help everyone stay in touch with USACO-related news.

Some advice and encouragement for our newest competitors and 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 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 Bill Cooperman, Jonathan Paulson, Richard Peng, and Nick (Huaiyu) Wu. A huge round of thanks is due to Mark Gordon, who not only coordinated the problem creation for this contest, but also re-designed our problem authorship environment to streamline the development of future contests. Thanks also to our translators for allowing us to offer this contest in six additional languages, to Clemson CCIT for providing our main contest server, and to our sponsors for their generous support: Usenix, Jump Trading, Dropbox, and D.E. Shaw.

We look forward to seeing everyone again in mid-January for our second contest of the season.

Happy coding!

- Brian Dean (bcdean@clemson.edu)