USACO February 2015 Contest -- Final Results

This was the third contest of our 2014-2015 contest season, the final contest before the US Open.

A total of 1884 participants submitted at least one solution, hailing from 69 different countries:

  814 USA  135 CHN   71 IRN   60 VNM   60 GEO   55 BLR   49 CAN
   43 BGD   38 ROU   38 BGR   35 KAZ   33 IND   32 SRB   29 TUR
   27 RUS   20 DEU   20 ARM   17 KOR   16 TKM   16 TJK   16 AUS
   14 UKR   14 MEX   13 HRV   12 JPN   12 FRA   11 TUN   11 COL
   10 ZAF   10 CUB    9 MKD    9 GRC    9 EGY    8 NLD    8 GBR
    8 FIN    7 POL    6 ISR    6 HUN    6 BEL    5 LTU    5 CZE
    5 BIH    4 THA    4 SGP    4 IDN    4 EST    3 AUT    3 VEN
    3 SYR    3 NZL    3 MYS    3 MDA    3 BRA    2 ALB    2 TWN
    2 LVA    2 ITA    2 ARG    1 CHE    1 AZE    1 SVK    1 MNG
    1 LUX    1 KGZ    1 IRL    1 ETH    1 ESP    1 CYP    

The average participant submitted solutions for 2.2 problems. In total, there were 4152 graded submissions, broken down by language as follows:

 1722 C++
 1120 Java
  841 C++11
  275 Pascal
   74 Python 2.7.6
   70 C
   45 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.

USACO 2015 February Contest, Gold

The Gold division had 391 total participants, of whom 291 were pre-college students. As you can see from the score distribution (with only 6 perfect scores!), this was by far the toughest gold contest of the year:

Detailed results for all gold participants are here.

1

Cow Hopscotch (Gold)
View problem  |   Test data   |   Solution

2

Censoring (Gold)
View problem  |   Test data   |   Solution

3

Fencing the Herd
View problem  |   Test data   |   Solution

USACO 2015 February Contest, Silver

The Silver division had 547 total participants, of whom 454 were pre-college students. The overall distribution for silver looked quite reasonable:

All competitors who scored 650 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

Censoring (Silver)
View problem  |   Test data   |   Solution

2

Cow Hopscotch (Silver)
View problem  |   Test data   |   Solution

3

Superbull
View problem  |   Test data   |   Solution

USACO 2015 February Contest, Bronze

The Bronze division had 946 total participants, of whom 741 were pre-college students. We saw a wide range of scores from the bronze participants this time, including quite a few very high scores:

All competitors who scored 650 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

Censoring (Bronze)
View problem  |   Test data   |   Solution

2

COW
View problem  |   Test data   |   Solution

3

Cow Hopscotch (Bronze)
View problem  |   Test data   |   Solution

Final Remarks

This was one of the more challenging gold contests we have given in recent history; silver and bronze were a bit more reasonable in terms of score distributions. Technically, this was one of the smoothest contests yet. The new grading platform seems to have reached a stable point with no issues reported this contest, and there were even hardly any clarification requests. I'm happy to see many students in bronze and silver being promoted -- and I wish all of you luck when you take the US Open in about a month!

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, Ben Cousins, Alex Yang, Richard Peng, Jonathan Paulson, 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 soon for the US Open, our national championship contest!

Happy coding!

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

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