USACO January 2015 Contest -- Final Results

This was the second contest of our 2014-2015 contest season. A total of 2084 participants submitted at least one solution, hailing from 72 different countries:

942 USA   169 CHN   75 IRN   68 VNM   63 CAN   54 BLR   
 52 IND    48 ROU   37 KAZ   35 UKR   31 RUS   31 BGR   
 29 MEX    29 BGD   24 TUR   24 GEO   20 AUS   18 KOR
 18 HRV    18 DEU   17 IDN   17 ARM   15 TKM   15 FRA  
 13 POL    13 EST   13 COL   10 SRB   10 SGP   10 JPN   
 10 EGY     9 GRC    9 BRA    8 NLD    7 ZAF    7 VEN    
  7 TWN     6 MDA    6 LTU    6 ITA    6 GBR    6 CUB
  5 THA     5 SYR    5 ISR    5 HKG    4 NZL    4 HUN    
  4 FIN     3 TJK    3 MYS    3 MKD    3 IRL    3 DOM    
  3 BIH     3 AUT    3 ARG    2 PRT    2 PER    2 KGZ    
  2 ESP     2 CZE    2 CYP    2 AZE    1 ZWE    1 TUN    
  1 SVK     1 NGA    1 MAR    1 LVA    1 ISL    1 CMR    
  1 ???

In total, there were 4971 graded submissions, broken down by language as follows:

 2039 C++
 1291 Java
 1002 C++11
  318 Pascal
  113 C
  108 Python 2.7.6
   81 Python 3.4.0

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. Note that we are using new grading servers running at half the speed of the originals, so all time limits have been doubled (and solutions have been re-graded accordingly); see the notes below for further details.

USACO 2015 January Contest, Gold

The Gold division had 366 total participants, of whom 247 were pre-college students. As in the December contest, we saw a wide range of scores in the gold results, with a large number of perfect scores:

Detailed results for all gold participants are here.

USACO 2015 January Contest, Silver

The Silver division had 450 total participants, of whom 364 were pre-college students. The score distribution for silver was quite reasonable:

All competitors who scored 600 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.

USACO 2015 January Contest, Bronze

The Bronze division had 1268 total participants, of whom 989 were pre-college students. We also saw a nice distribution across the entire range of scores in bronze:

All competitors who scored 600 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.

Final Remarks

Another largely successful contest! I'm quite happy with the level of participation, the overall score distributions, and the number of promotions we are seeing. There is clearly a lot of programming talent out there!

There was only one "glitch" with this contest on the technical side. Everything ran smoothly for the first 3 contest days, but we saw an unprecedented spike in load on Monday (perhaps due to the MLK holiday in the USA), which caused submissions to queue for a long time. During the 1..2 hours this happened, feedback was slow to arrive, and worse, due to load-related slowdowns, some compilations timed out, resulting in not-so-helpful "compilation failed" messages being returned. To fix things, I've swapped out our pool of grading servers for a new set of machines that should be much more reliable in terms of load. The new servers run twice as slow as the original servers, though, so I've doubled the time limits for this contest and re-graded everything; hence, you'll notice your code now taking twice as long when you submit it in "analysis" mode. For some submissions that were right at the time limit borderline, it is possible for solutions previously judged during the contest with "time limit exceeded" to be accepted, and vice-versa. Note that since our grading servers have changed speeds, it will now be necessary for us to accordingly re-calibrate the timings on all of our historical contests -- this will take place over the next few weeks, so do not be alarmed if timing on older contests seems off for a short while.

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, Josh Brakensiek, Jonathan Paulson, Danny Sleator, Richard Peng, Chun Wu, Yinzhan Xu, 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, Jump Trading, Dropbox, and D.E. Shaw.

We look forward to seeing everyone again in late February for our third contest of the season.

Happy coding!

- Brian Dean ([email protected])
Director, USA Computing Olympiad
Associate Professor of Computer Science, Clemson University

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