Solutions in C to the puzzles of Advent of Code 2019.

• make to build all executables
• make run to run all solvers
• make <day> (e.g. make 1) to run the program solving the puzzle of the specified day
• make test to run all tests
• make time to run all solvers and print timings
• make clean to remove all files generated by make

In addition, debug=1 and/or CC=<compiler> can be used as arguments to make. For example, make clean; make debug=1 CC=clang test will run all tests after building all solvers using clang with additional warnings and flags for debugging. By default, compilation is done with gcc.