ICFP Programming Contest 2015

This is the 18th instance of the annual programming contest series sponsored by the ACM SIGPLAN International Conference on Functional Programming (ICFP).

The contest ran from Friday 7 August 2015 at 12:00 UTC to Monday 10 August 2015 at 12:00 UTC. The lightning division ended on Saturday 8 August 2015 at 12:00 UTC. The winners were announced on 1 September 2015 at ICFP 2015, and a video of the award presentation is available. The winners were:

• First Place: Team Unagi
  We officially declare that C++, Java, C#, PHP, Ruby and Haskell are the programming tools of choice for discriminating hackers!
• Second Place: Team Natsubate!
  We officially declare that C++, Python and JavaScript are fine programming tools for many applications!
• Third Place: Team ByCode
  We officially declare that C++11 is not too shabby!
• Lightning Division: Team Frictionless Bananas
  We officially declare that C++ is very suitable for rapid prototyping!
• Judge's Prize: Team WILD BASHKORT MAGES
  We officially declare that the WILD BASHKORT MAGES are an extremely cool bunch of hackers!

These are the leaderboards for the qualifying and final rounds of both the full contest and the lightning division:

• Qualifying Leaderboard
• Final Leaderboard
• Lightning Division Qualifying Leaderboard
• Lightning Division Final Leaderboard

In addition to the contest information available below, all contest-related artifacts except for contestant submissions and the actual judging runs are now available on GitHub. Follow @ICFPContest2015 on Twitter for contest updates (also embedded below). Informational tidbits and any necessary rule clarifications will appear on Twitter and be posted below. Email icfpcontest2015@gmail.com (or tweet to @ICFPContest2015, for public disclosure) if you have questions, comments, or exhortations. During the contest, many contest organizers monitored the #icfp-contest channel on irc.freenode.net; their nicks are galois_dmwit, galois_dmz, galois_jesse, galois_joey, galois_kiniry, and galois_yav.

• Original BAA Solicitation
• Background
• Problem Specification
• Qualification Problems
• Team Writeups
• IRC Channel Log
• ICFP Contest 2015 GitHub

Intellectual Property

ICFP contest participants retain ownership of all intellectual property rights in and to any submitted solutions, custom tools, and related materials ("Submissions") that participants had before submission. As a condition of entry, participants grant Galois, Inc. a non-exclusive, perpetual, irrevocable, worldwide, royalty-free license to use, reproduce, publish, distribute, publicly perform and publicly display the Submissions for the purposes of allowing Galois, Inc. and other ICFP judges to test and evaluate the Submissions for purposes of the contest.

Tidbits and Clarifications

• (2015-08-10 12:15 UTC) The qualification round has ended, and the final qualification scoreboard has been posted. There were nearly 1.25 million solutions submitted by over 300 teams, with nearly 800 participants overall. Further information about the final round, the contest organization/infrastructure, and the fate of the universe will be forthcoming over the weeks leading to the announcement of the winners at ICFP 2015. Thanks to all recruits for your participation, enthusiasm, and dedication!
• (2015-08-10 07:45 UTC) ALERT: At this point, over 1.15 million solutions have been submitted by over 300 teams. Our preliminary analysis of the discovered davar indicates that Stross was mistaken; they will delay the inevitable ████████████████████ scenario by 63 months.
• (2015-08-09 11:00 UTC) ALERT: A bug that caused the leaderboard to sometimes report unexpectedly high scores—possibly related to including two solutions for a single problem and seed in a single submission—has been fixed. Rankings have been adjusted.
• (2015-08-09 11:00 UTC) The formless spawn have transformed one of the undiscovered words of power, reshaping it in the image of their master!
• (2015-08-08 23:00 UTC) A sample command sequence for problem 6, seed 0 can be found in problem6-seed0.txt. This sequence has 1,180 commands (which is why we have not posted it directly on this page). It results in a score of 3,261, does not cause an error, and does not contain any phrases of power. Video for this command sequence is available as well.
• (2015-08-08 22:05 UTC) ALERT: It has come to our attention that participants have submitted many solutions using seeds that were not provided by AS2H2. Unfortunately, this has caused elements of the scoring system evaluating those solutions to be swallowed by the gibbering darkness. We are taking actions to mitigate this issue by filtering out such unsafe solutions. We hope to have the leaderboard back online soon. In the meantime, be aware that repeatedly submitting solutions with unapproved seeds may lead to... consequences. For you, and anyone within a 10-mile radius.
• (2015-08-08 21:30 UTC) ALERT: The leaderboard is down temporarily as we make adjustments to improve the performance of evaluation of submissions. We are nearing 300 teams and 200K submissions.
• (2015-08-08 17:45 UTC) RULES CLARIFICATION: Power phrases must be pronounced precisely, and in their original tongue---not in isomorphism thereof. Agents may notice subtle shifts in their mana.
• (2015-08-08 12:00 UTC) ALERT: It has come to the attention of ██████████ that there is considerable risk of an unintentional summoning event in Vancouver in early September. Because Vancouver borders their domain, they have invoked the Benthic treaty and demanded extra precautions. Thus, we have added problem 24 to the set.
• (2015-08-07 23:30 UTC) RULES CLARIFICATION: Sequences of commands that do not result in one of the three game-ending conditions described in the specification are allowed. They are scored in exactly the same way as other sequences.
• (2015-08-07 23:00 UTC) A sample play for board 6, seed 0 is rendered at the Galois Vimeo channel.
  (2015-08-08 17:00 UTC) Note that, due to bug fixes in the evaluation server, the command sequence earlier provided is no longer valid for this animation.
• (2015-08-07 21:00 UTC) The unpredictability of the eldritch forces involved makes it impossible for us to provide precise information on time and memory resource availability during the time of final judgement. However, we can guarantee that sufficient resources will be available to accommodate the overhead of any earthly programming language or runtime system.
• (2015-08-07 21:00 UTC) We have added an optional flag, -c, to the command line parameters. If supplied, it indicates how many processor cores are available. Teams may wish to use this when implementing parallel solutions.
• (2015-08-07 21:00 UTC) RULES CLARIFICATION: Despite a tweet earlier in the day implying that board sizes are bounded by the size of the largest currently-posted problem, there is no fixed constraint on board sizes. There is also no fixed constraint on unit sizes.
• (2015-08-07 21:00 UTC) RULES CLARIFICATION: When determining whether all members and the pivot have been moved "to locations that they have previously occupied", all members are treated identically. For example, rotating the unit shown on the specification page 3 times in place constitutes an error.
• (2015-08-07 21:00 UTC) RULES CLARIFICATION: Each occurrence of a phrase of power—even if that occurrence overlaps with another occurrence of the same phrase of power—is counted. For example, if "cthulhu cthulhu" is a phrase of power, then the sequence of commands "cthulhu cthulhu cthulhu" contains two occurrences.
• (2015-08-07 17:15 UTC) SCORING CLARIFICATION: Be mindful of the fact that scores on a problem leaderboard are averages of the scores across all seeds for the problem, and seeds for which no solution is submitted score 0 points.
• (2015-08-07 17:15 UTC) RULES CLARIFICATION: The question of what happens after death is one of the ancient mysteries, to which mankind has never found a definitive answer. However, for the purposes of this competition, programs that are killed for violating resource limits will earn scores of 0 for their runs. The judges may, at their discretion, extend resource limits during the judging process; especially promising programs that are terminated before reaching their full potential may be reincarnated with more resources.
• (2015-08-07 17:15 UTC) SPEC CLARIFICATION: The command line parameter "-p" is a phrase of power, as a string. Your program should not strip quotation marks from it. Your shell may require you to add quotation marks to it, or escape parts of it, when invoking your program.
• (2015-08-07 15:30 UTC) RULES CLARIFICATION: The sequence of random numbers to be used for unit selection is computed from all generator states, including the seed. This is why the example starts with 0.
• (2015-08-07 15:15 UTC) AS2H2 have created "Galois Live Test Team" for internal assessment purposes. Its results will not be counted in the final standings.
• (2015-08-07 15:15 UTC) It seems that our scoring system was not properly tuned for the primal powers unleashed by certain submissions. We have made appropriate adjustments, and scores for all submissions have been recalculated.
• (2015-08-07 15:15 UTC) RULES CLARIFICATION: A sequence of commands that continues after the game ends (the last piece has been played, or the starting position of the next piece would be invalid) is an error, and results in a score of 0 points.
• (2015-08-07 15:15 UTC) If you receive an error that "Only GET or HEAD is supported" from the submission server, this likely means that your JSON is malformed. Check your capitalization and formatting carefully. While the fundamental forces of the universe are unperturbed by these minor issues, our (maintained by mere mortals) submission system is very sensitive to such.
• (2015-08-07 13:00 UTC) If a submitted program requires a platform other than Linux, we will obtain and use it. We have a wide array of systems at our disposal, including those of Microsoft and Apple. However, Linux-based submissions will be faster for us to evaluate, so we can take less time away from our world-protecting duties.

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