The name of your .c file should be database.c
And please compress the database.h together with database.c into one zip file

On manual the PRINT query will output course name deadline difficulty, but on JOJ it's Course Name Deadline Difficulty. Sorry for the inconsistency :(

Humane: Close to the real testcases in Lab.
Cold Blood: Extreme testcases given by the cruel TA.
Note: Actually they are only different in size, there is no essential difference.