C++ Solutions for adventofcode.com year 2021 puzzles
No clean code or best practices here, I just tried to freshen up my modern C++ skills.
To compile, this should work for all puzzles (actually, C++20 is only needed for a few, C++11 should be enough for most):
g++ -O2 -std=c++20 puzzleXY_Z.cpp -opuzzleXY_Z