This is a simple arithmetic puzzle.
The .txt files provide the steps needed to win 3x3 and 4x4 puzzle.
You can pass them as input to your programm, in order to solve itself automatically.
./fifteen 3 < YOUR_PATH/3x3.txt for the 3x3 puzzle
./fifteen 3 < YOUR_PATH/4x4.txt for the 4x4 puzzle
where YOUR_PATH is the path with vinegere.c and the txt files
To download the CS50 library and learn more about it, go here