Given the price of n stocks and the future price, find the maximum return that can be achieved under a certain budget. For example, if you have 4 dollars, 4 stocks are currently worth [1,1,1,4], and in the future, these 4 stocks will appreciate to [2,2,2,6]. At this time, if you buy the first three stocks, Spend 3 dollars to reach the maximum profit of 3 dollars (2-1) + (2-1) + (2-1). n is limited to 1 to 300, and the budget is limited to 1 to 30000.
