计算学分。可由本科生类派生出研究生类，但它们各自的从课程学时数折算为学分数的算法是不同的，本科生是16个学时一学分，而研究生是20个学时一学分。输入课程名称、课时，求学分。-To calculate of the credit.The undergraduate class derived class graduate, but each of them from the course hours converted into fraction algorithm is different,