This problem is related to a reservation system where customers book a service and pay it in one or more transactions which may happen on different dates.
Your job is to reorganize the items in the table by sales amount (quantity * price). Reorganize the items from left to right, bottom to top. The item with the highest sales amount should come on top left of each invoice.
Here is another scheduling problem that deals with the allotment of classrooms for various training programs. Your chalenge is to read the source data and build an output result set that shows the weekly schedule of each training topic and the class room in which training is scheduled.