Advent of Code 2019

My solutions to the Advent of Code 2019.

Please note that this code has been written on a Linux system, using Clang version 9 as the compiler.

Running

Each day_<DD>/ dir is a standalone project and contains the solutions for one Advent of Code 2019 day.

The build can be launched with (Day 1 as an example):

$ mkdir day_01/build && cd day_01/build
$ cmake -DUNITTESTS_ENABLED=ON -DCMAKE_BUILD_TYPE=Debug ../
$ make -j $(nproc)

The executable day_01 executes the actual puzzles. It's called like this:

$ day_01 1|2 <INPUT_FILE>

It will read the <INPUT_FILE> and run either part 1 or part 2 of the puzzle, depending on which part has been choosen as the first parameter.

Furhtermore, an executable day_01_ut is produced. It runs the UTs for the day, written with the Catch2 UT framework.

A recompilation and rerun of the UTs can also be started by running make check. The additional target check_valg will also rebuild the UT as necessary, but will run it under Valgrind.

Common

The common/ directory contains some useful code shared amongst the implementations for the Advent of Code days to reduce boilerplate code writing.

AoC Exceptions

The file common/aoc_except.hpp contains a few exceptions specifically for AoC:

• FileNotFound: Pretty much what the name says. Uses a runtime_error with a custom string message based on the path handed to its initializer.
• AoCError: Just a child inheriting from runtime error to distinguish my own exceptions in try-catch blocks.

The Tokenizer

The tokenizer, which can be found in common/Tokenizer.hpp, is a tool to read in a ASCII text file or String, and tokenize it by a specific delimiter and store the tokens as a specific type.

To that end, the Tokenizer's TType template argument sets the type of token to store. Tokens are taken from the String or filepath provided in the constructor. It cannot be changed after initialization.

The string is tokenized when the tokenize(const char& delim) is called, splitting it at each occurence of delim. The tokens are then coverted to TType and stored. Calling tokenize() with another delimiter will clear the current tokens and retokenize the input according to the new delimiter.

The conversion to TType is implmented currently for TTypes which are convertible to std::string as well as those TType which can be converted from string via the std::from_chars function.

Just implementing a single constructor accepting const std::string& should suffice to allow usage of user defined classes without any adaptations to the Tokenizer class itself.

The converted tokens are made available via standard begin/end members, which also makes Tokenizer amendable to use in ranged for loops. In addition, the tokens function can be used to get a copy of the entire container of tokens, in case the user wishes to mutate them.

Templating

The template.sh script provides a small scaffolding mechanism to provide easy generation of new project skeletons for AoC Day puzzles.

The approach taken here is that each AoC 2019 day is its own independent project. The script uses Advent of Code 2019 to realize the templates in template/.

Invocation

~$ template.sh <TARGET_DIR> <DAY> <NAME> 

It is important to note that the script will exit if the <TARGET_DIR> already exists. Furthermore, <DAY> has to have the form DD, e.g. 01 or 22. Finally, <NAME> must be a valid filename in your OS.

When executed, template.sh does the following:

• Create <TARGET_DIR>
• Template the files in ./template with the values given in <DAY> and <NAME>
• Create <TARGET_DIR>/build
• Run cmake -S <TARGET_DIR> -B <TARGET_DIR>/build -DUNITTESTS_ENABLED=ON -DCMAKE_BUILD_TYPE=Debug
• Run make -j $(nproc) on the newly created build dir
• Create a symlink <TARGET_DIR>/build/compile_commands.json -> <TARGET_DIR>/compile_commands.json for use by C++ tooling