enter:
Parameter 1, positive array costs
Parameter 2, positive array profits
Parameter 3, positive number k
parameter 4, positive number m
costs[i] represents the cost of item i
profits[i] represents the money (profit) that the item i can earn after deducting expenses
k means that you cannot do at most k projects in parallel and can only be done in series. m means your initial capital
description: every time you finish a project, the income you get immediately can support you to do the next project.
Output: The maximum amount of money you last earned.