profits.hs

--My initial solution, but I realized that maybe repeatedly calling maximum wasn't good
profits :: [Int] -> [Int]
profits (x:y:ys) = (maximum (xs) - x) : profits (xs)
	where xs = y:ys
profits _ = []

--My updated solution that is slightly more complex
--But it keeps track of the current maximum until that current maximum is outdated
profits' :: [Int] -> Int -> [Int]
profits' (x:y:ys) cm = 
	if x == cm 
		then profits' xs (maximum xs)
		else (cm - x) : (profits' xs cm)
	where xs = y:ys
profits' _ _ = []

--Just to test things out
prices :: [Int]
prices = [10, 30, 42, 15, 20, 50, 10, 25] -- 40
prices' :: [Int]
prices' = [30,21,34,52,67,32,45,67,25,78,31,54,64,22]  -- 57

main = do
	print $ (maximum . profits) prices
	print $ (maximum . profits) prices'
	print $ (maximum (profits' prices (maximum prices)))
	print $ (maximum (profits' prices' (maximum prices')))