Go to file
2021-01-01 15:52:53 -08:00
console.cr Factor console code into a separate file. 2020-12-11 11:32:01 -08:00
day1.cr Update code to use advent lib. 2020-12-05 16:06:51 -08:00
day1.ijs Add day 1 and 2 solutions in J. 2020-12-23 21:47:05 -08:00
day1.v Add day 1 part 1 formalized in Coq. 2020-12-01 19:44:47 -08:00
day2.cr Update code to use advent lib. 2020-12-05 16:06:51 -08:00
day2.ijs Add day 1 and 2 solutions in J. 2020-12-23 21:47:05 -08:00
day3.cr Update code to use advent lib. 2020-12-05 16:06:51 -08:00
day3.ijs Add day 3 solution in J. 2020-12-23 21:46:46 -08:00
day4.cr Update code to use advent lib. 2020-12-05 16:06:51 -08:00
day5.cr Update code to use advent lib. 2020-12-05 16:06:51 -08:00
day5.ijs Add J solution for day 5. 2020-12-23 22:40:42 -08:00
day5g.cr Update code to use advent lib. 2020-12-05 16:06:51 -08:00
day6.cr Clean up some solutions. 2020-12-07 23:38:38 -08:00
day7.cr Clean up some solutions. 2020-12-07 23:38:38 -08:00
day8.cr Factor console code into a separate file. 2020-12-11 11:32:01 -08:00
day8.v Add experimental formalization of (inefficient) solution. 2020-12-13 23:32:11 -08:00
day9.cr Add day9 solution. 2020-12-08 21:34:39 -08:00
day10.cr Add solutions to days 10 and 11 2020-12-11 11:32:33 -08:00
day11.cr Add solutions to days 10 and 11 2020-12-11 11:32:33 -08:00
day12.cr Clean up day 12. 2020-12-12 01:44:04 -08:00
day13.cr Add day 13 solution. 2020-12-12 22:09:28 -08:00
day14.cr Add day 4 solution. 2020-12-13 21:53:37 -08:00
day15.cr Add updated solutions, including day 20. 2020-12-20 00:31:30 -08:00
day16.cr Add unclean day16 solution. 2020-12-15 22:05:25 -08:00
day17.cr Add updated solutions, including day 20. 2020-12-20 00:31:30 -08:00
day18.cr Add updated solutions, including day 20. 2020-12-20 00:31:30 -08:00
day19.cr Add updated solutions, including day 20. 2020-12-20 00:31:30 -08:00
day20.cr Add updated solutions, including day 20. 2020-12-20 00:31:30 -08:00
day21.cr Add solutions to day21 and day22. 2020-12-21 22:40:37 -08:00
day22.cr Add solutions to day21 and day22. 2020-12-21 22:40:37 -08:00
day23.cr Add day 23. 2020-12-23 21:46:32 -08:00
day24.cr Add day24 solution. 2020-12-23 21:44:32 -08:00
day25.cr Add day 25 solution. 2020-12-29 00:50:26 -08:00
input.sh Add a script to pull input from AoC 2020-12-02 20:47:58 -08:00
passports.cr Reimplement day 4 using validators. 2020-12-04 19:54:14 -08:00
README.md Add README. 2021-01-01 15:52:53 -08:00
shard.yml Extract some common utilities into a library. 2020-12-05 15:36:08 -08:00
template.cr Make changes to the template. 2020-12-11 11:32:12 -08:00

Advent of Code 2020 Solutions

Here's to my first 50 star year since 2017! The goal was to make it to top 100 at least once this year, and it finally came true on day 22 (and again in day 25 part 2, but that hardly counts). Honestly, I am not at all happy with myself, though.

Kinds of Solutions

I "raced" in Crystal, but also tried my hand at formal verification in Coq, and tried out an APL dialect called J for fun. I didn't always clean my race day solutions, particularly the ones to the "hard" days. I will write about my Coq solutions on my site.

Rankings

Here's the (rather embarassing) table with my times.

      -------Part 1--------   -------Part 2--------
Day       Time  Rank  Score       Time  Rank  Score
 25   00:07:18   105      0   00:07:24    94      7
 24   00:25:27  1496      0   00:43:46  1165      0
 23   00:27:30   887      0   01:35:00  1057      0
 22   00:03:44    42     59   01:16:52  2242      0
 21   00:21:57   612      0   00:26:05   439      0
 20   00:27:52   465      0   03:00:50   845      0
 19   00:14:56   123      0   00:48:50   439      0
 18   00:26:17  1209      0   00:28:01   574      0
 17   00:17:23   400      0   00:19:14   281      0
 16   00:11:50   627      0   01:03:40  2040      0
 15   00:18:11  1772      0   00:30:38  1924      0
 14   00:18:05  1220      0   00:39:57  1173      0
 13   00:04:59   198      0   01:05:11  1606      0
 12   00:06:19   206      0   00:14:17   245      0
 11   00:13:23   414      0   00:19:11   261      0
 10   00:05:04   293      0   00:31:04  1493      0
  9   00:08:55  1721      0   00:26:50  3540      0
  8   00:04:23   275      0   00:09:56   256      0
  7   00:17:46   832      0   00:24:22   615      0
  6   00:03:31   385      0   00:09:38   999      0
  5   00:08:21   839      0   00:27:23  3404      0
  4   00:07:40   786      0   00:20:26   440      0
  3   00:02:46   119      0   00:07:40   448      0
  2   00:03:48   341      0   00:06:01   272      0
  1   00:07:52  1072      0   00:09:00   748      0

Crystal for Competitive Programming

I really enjoyed writing Crystal for the Advent of Code, but there were a few reasons why it wasn't perfect for the task.

  • When you're not banking on brute force speed, you lose some time to the compiler.
  • Numbers are always 32-bit by default, and require constant _i64 suffixes everywhere in the code when they're involved.
  • Type annotations (however necessary they are) for hashes and arrays make refactoring a little bit slower.