Advent of Code in Go

A handy template repository to hold your Advent of Code solutions in Go (golang).

Advent of Code (https://adventofcode.com) is a yearly series of programming questions based on the Advent Calendar. For each day leading up to christmas, there is one question released, and from the second it is released, there is a timer running and a leaderboard showing who solved it first.

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Features

• A directory per question <year>/<day>
• Auto-download questions into <year>/<day>/README.md
• Auto-download example input into <year>/<day>/input-example.txt
• With env variable AOC_SESSION set:
  • Auto-download part 2 of questions into <year>/<day>/README.md
  • Auto-download user input into <year>/<day>/input-user.md
  • Only runs part 2 once part 1 is completed
• When you save code.go, it will execute your run function 4 times:
  • Input input-example.txt and part2=false
  • Input input-example(2).txt and part2=true
  • Input input-user.txt and part2=false
  • Input input-user(2).txt and part2=true
  • Each run will display the return value and timing.
  • Part 2 will use the <file>2.txt if it exists.
• Control execution with PART= INPUT= ./run.sh <year> <day>, where
  • PART can be 1 or 2, and
  • INPUT can be example or user

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Usage

1. Click "Use this template" above to fork it into your account

2. Setup repo, either locally or in codespaces

   • Locally
     • Install Go from https://go.dev/dl/ or from brew, etc
     • Git clone your fork
     • Open in VS Code, and install the Go extension
   • Codespaces
     • Click "Open in Codespaces"

3. Open a terminal and ./run.sh <year> <day> like this:

   $ ./run.sh 2023 1
   Created directory ./2023/01
   Created file code.go
   Created file README.md
   Created file input-example.txt
   run(part1, input-example) returned in 616µs => 42

4. Implement your solution in ./2023/01/code.go inside the run function

   • I have provided solutions for year 2022, days 2,4,7 – however you can delete them and do them yourself if you'd like

5. Changes will re-run the code

   • For example, update code.go to return 43 instead you should see:

   file changed code.go
   run(part1, input-example) returned in 34µs => 43

6. The question is downloaded to ./2023/01/README.md

7. Login to https://adventofcode.com

8. Find your question (e.g. https://adventofcode.com/2023/day/1) and get your puzzle input and save it to ./2023/01/input-user.txt

   • See Session below to automate this step

9. Iterate on code.go until you get the answer

10. Submit it to https://adventofcode.com/2023/day/1

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Session

Optionally, you can export AOC_SESSION=<session> from your adventofcode.com session cookie. That is:

• Login with your browser
• Open developer tools > Application/Storage > Cookies
• Retrieve the contents of session
• Export it as AOC_SESSION

With your session set, running code.go will download your user-specifc input-user.txt and also update README.md with part 2 of the question once you've completed part 1.

Currently, your session is NOT used to submit your answer. You still need to login to https://adventofcode.com to submit.