It is calculated by the bed, just like the bed in the dormitory, which seems to be 40 yuan per bed. There are four rooms, six rooms, eight rooms and so on. The conditions are not very good, but the accommodation is also convenient.
More beds are naturally cheaper, and more beds are available for boys.
If you check in the same day, ask the same day. There are usually vacant rooms.
When you get to school, ask any student and you should find them.