From these, > ... I ended up ... neither a zero-day ... > Realizing everyone in the class would fail, the professor changed the grade of this project to only

From these, > ... I ended up ... neither a zero-day ... > Realizing everyone in the class would fail, the professor changed the grade of this project to only account for 30% of the grade. > I ... disregarding the rest of the busy work for the class. It sounds like OP could not find a zero day (old_grade=0) and did not do any other homework (new_grade=0), therefore should have received max(0, 0), but received a C.