## 2017 US Open Contest -- Final Results

This was our final contest of the 2016-2017 season, and also our national championship -- given high weight during selection of finalists to attend our summer training camp. A total of 2003 distinct users logged into the contest during its 4-day span. Of those, 1616 participants submitted at least one solution, hailing from 66 different countries:

  926 USA  132 CHN   53 VNM   43 GEO   28 CAN   24 BLR   23 IRN
22 UKR   22 MEX   21 FRA   19 KOR   19 IND   15 HRV   14 RUS
11 THA   11 KGZ   11 HUN   11 GRC   11 BGR   10 TUN   10 ROU
10 DEU   10 BGD    9 SGP    9 EST    9 ARM    8 GBR    7 TKM
7 SYR    7 IDN    7 CUB    6 ZAF    6 POL    6 IRL    6 AUS
5 TUR    5 JPN    5 ITA    5 HKG    5 FIN    5 BRA    4 TWN
4 MNG    4 ARG    3 SVN    3 NLD    3 COL    2 MYS    2 LTU
2 EGY    1 TJK    1 SVK    1 SRB    1 PRT    1 NZL    1 MDA
1 MAC    1 LUX    1 ISR    1 ESP    1 CMR    1 BOL    1 BIH
1 AZE    1 AUT    1 ATG


The average participant who submitted code submitted solutions for 1.9 problems. In total, there were 2997 graded submissions, broken down by language as follows:

 1118 C++11
1109 Java
586 C++
74 Python 3.4.0
56 Python 2.7.6
25 Pascal
17 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 2017 US Open Contest, Platinum

The Platinum division had 536 total participants, of whom 407 were pre-college students. By design, the platinum problems were quite challenging, and only a handful of students received high scores. Congratulations in particular to the 18 perfect scorers worldwide, 3 of whom hail from the USA! A list of top-scoring students is here.

# 1

Modern Art
View problem  |   Test data   |   Solution

# 2

Switch Grass
View problem  |   Test data   |   Solution

# 3

COWBASIC
View problem  |   Test data   |   Solution

## USACO 2017 US Open Contest, Gold

The Gold division had 501 total participants, of whom 418 were pre-college students.

All competitors who scored 750 or higher on this contest are automatically promoted to the platinum division. Detailed results for those promoted are here. You will notice that one of the original problems (the first "modern art" problem) is no longer in the lineup; we unfortunately had to revoke this problem since an algorithmic flaw was identified that invalidates the solution approach we had in mind -- making the problem far harder than intended (in a nutshell, we had intended this to be a longest path problem in a DAG, but the underlying graph was unfortunately not a DAG since in some cases you cannot tell for two overlapping colors whether one was on top of another or vice versa). Scoring and promotion for gold is therefore based on just two problems, although for fairness we also promoted anyone who would have had 750 points with the third problem factored in as well.

# 1

Bovine Genomics
View problem  |   Test data   |   Solution

# 2

Modern Art 2
View problem  |   Test data   |   Solution

## USACO 2017 US Open Contest, Silver

The Silver division had 579 total participants, of whom 477 were pre-college students.

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

Paired Up
View problem  |   Test data   |   Solution

# 2

Bovine Genomics
View problem  |   Test data   |   Solution

# 3

Where's Bessie?
View problem  |   Test data   |   Solution

## USACO 2017 US Open Contest, Bronze

The Bronze division had 536 total participants, of whom 413 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

The Lost Cow
View problem  |   Test data   |   Solution

# 2

Bovine Genomics
View problem  |   Test data   |   Solution

# 3

Modern Art
View problem  |   Test data   |   Solution

## Final Remarks

I am quite happy with the results from the US Open this year. The contest was designed to challenge students at all levels, and as a result, score distributions were somewhat sparse at the top (this is useful in particular for platinum, to help us differentiate top competitors when it comes to our camp selection process). Despite the challenging problems, however, I'm glad to see many competitors earning substantial partial credit. There is an amazing amount of computing talent out there! From a technical perspective, the contest ran quite smoothly, modulo two short-lived load spikes that are being examined more closely to make sure they don't re-occur on other contests. We also had to revoke one of our gold problems after a fundamental algorithmic flaw was identified, making it likely NP-hard to solve (this is rare with USACO contests due to our relatively strict quality control measures, but unfortunately sometimes bugs still slip through!) Scoring and promotion in gold for this contest is therefore based on 2 problems instead of 3.

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, Travis Hance, Mark Chen, Lewin Gan, Jonathan Paulson, and Nathan Pinsker. 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, D.E. Shaw, Jump Trading, and Ansatz Capital.

I'd like to send a special acknowledgement to Richard Peng. After earning medals in the 2004 through 2006 IOIs, he has been one of our most prolific coaches for the past decade. As Richard is now a computer science professor at Georgia Tech and one of the very top research leaders of his field, he has decided to step down from coaching in the USACO; we'll definitely miss you and your amazing contributions, Richard -- and thanks for so much enthusiasm and support over the past years! USACO depends vitally on its superb coaching staff for running all its activities, and we are especially indebted to those who have contributed for many years.

The coaching staff are currently deliberating about camp selection and should have our list of finalists announced within a few weeks time.

Happy coding!

- Brian Dean (bcdean@clemson.edu)