This is a free-to-use template for Advent of Code programs! All I ask is that you leave the LICENSE file intact (though you may rename it and apply your own license to the resulting repository).

The template is set up so that you can jump straight into coding the solutions without worrying about the boilerplate to run it. There is a little bit of fine print to that, though.

Usage

For each day:

1. All input data goes in the folder AoC/data/dayX, where X is the number of the day (without leading zeroes).
   1. Examples should be files named example*.txt, where * can be replaced with anything. These example files should contain the expected answer for part 1 on the first line, part 2 on the second line, and then the actual input starts with the third line. Either line can also be set to \SKIP to set the SkipPart1 or SkipPart2 flags in your code, if needed. (If the expected answer starts with a backslash, write two backslashes at the start. Don't escape backslashes in the expected answer otherwise.)
   2. The actual puzzle input should be in a file named input.txt. It does NOT have the leading "expected answer" lines - you can (and should) directly save the "get your puzzle input" file to the expected path.
2. For each day, you will need to create a public class named DayX, where X is the number of the day (without leading zeroes). This class must derive from AdventDay, and contain a Run method that takes a single StreamReader.
   1. This StreamReader is set to the start of the puzzle or example input. For examples, it will be positioned past the expected answers, at the start of the third line.
   2. Within the Run method, set the Part1String or Part1Number to the answer your code comes up with. Same for Part2.
3. Run the program.
   1. Using "Latest" will run the highest-numbered available day; "Main" will prompt you to input a day.
   2. The runner will run your code against all example inputs first.
   3. If an expected answer is specified, and the given answer doesn't match it, you'll be told what the actually-given answer was, and the program will exit upon the conclusion of all example tests (without running on your input data!).
   4. If all examples' given answers match the expected answers, then the program will run your code on the actual input data, and give you those answers as well.

REPL Usage

Another thing you can do, new to this version of my AoC template, is to run the code as part of a Read-Eval-Print Loop. If you're doing this, I recommend using CSharpREPL. You can then run your code for a given day, for example day 1, as follows (relative paths assume you opened the csharprepl at the root of this repository):

#r "AoC/AoC.csproj"
using Nixill.AdventOfCode;
Day1 day1example1 = Program.RunDay<Day1>("AoC/data/day1/example1.txt");

Once you've done so, you are free to inspect any public members of the output at your leisure.

AdventDay Class

The AdventDay class contains the following accessible members:

• string InputFilename (get): The input filename for a given iteration of the code. Ideally not used, but some puzzles do have slightly different rules between examples and actual input.
• bool SkipPart1 and SkipPart2: Usually false; if true, a given example has indicated that one part or the other should be skipped on that input. Mostly usable for part 1 examples that aren't designed to carry into part 2. Always false for real puzzle input.
• bool Part1Complete and Part2Complete (get): Whether or not an answer has been provided by your code for a given part.
• string Part1Answer and Part2Answer (get): The answer provided by your code, if any. Throws an exception if that part is not complete. Cannot be directly set, use the following properties instead.
• string Part1String and Part2String: The answer provided by your code, as a string. When set, that part is marked as complete.
• long Part1Number and Part2Number: The answer provided by your code, as a number. When set, that part is marked as complete.

Access notes:

• SkipPart1 and SkipPart2 are internally, but not publicly, settable.
• Part1String, Part2String, Part1Number, and Part2Number are protected, not publicly accessible.

AdventExtensions Class

The AdventExtensions static class contains the following extension methods on StreamReader:

• IEnumerable<string> StreamReader.GetLines(): Gets an enumerator over the lines of the input.
• string[] StreamReader.GetAllLines(): Gets an array of all the lines of the input.
• string StreamReader.GetEverything(): Gets the entire input.
• IEnumerable<string> StreamReader.GetLinesOfChunk(): Gets an enumerator over the lines of the next chunk of the input.
• IEnumerable<IEnumerable<string>> StreamReader.GetChunksByLine(): Gets an enumerator over all the chunks of the input.
• IEnumerable<string> StreamReader.GetWholeChunks(): Gets an enumerator over whole chunks.
• Grid<char> StreamReader.CharacterGrid(): Returns the entire input as a single grid of characters.
• Grid<char> StreamReader.CharacterGridChunk(): Returns the next chunk of input as a single grid of characters.
• Grid<T> StreamReader.Grid(Func<char, T>): Returns the entire input as a single grid. The parameter maps a character to something else.
• Grid<T> StreamReader.GridChunk(Func<char, T>): Returns the next chunk of input as a single grid of characters. The parameter maps a character to something else.

With the following notes/caveats:

• If the input file ends with a blank line, this line is ignored.
• One chunk is one or more non-empty lines, broken by empty lines. The empty lines separating chunks are not returned.
• All of those methods run from the current position within the input.

And the following other extension methods:

• T T.AssignTo(out T): Assigns a value to a variable inline, returning it.
• void IGrid<char>.PrintGrid(): Prints a character grid to the console.

Other notes

Note that the folder AoC/data is .gitignored. This is intentional, as Advent of Code requests that puzzle inputs not be shared. You can remove that if you're committing to a private repository; otherwise, if you need to version-control your input data, you should look into submodules.

If you've used either of my previous templates, this new format is mostly incompatible with both. However, the data folder structure remains the same as it did in Template3.

Template2 doesn't exist. Don't ask. ☺