Max Profit

I grabbed Apple's stock prices from yesterday and put them in a list called stock_prices, where:

The indices are the time (in minutes) past trade opening time, which was 9:30am local time. The values are the price (in US dollars) of one share of Apple stock at that time. So if the stock cost $500 at 10:30am, that means stock_prices[60] = 500.

Write an efficient function that takes stock_prices and returns the best profit I could have made from one purchase and one sale of one share of Apple stock yesterday.

For Example:

stock_prices = [10, 7, 5, 8, 11, 9]
get_max_profit(stock_prices) ==  6 # because we buy for $5 and sell for $11

No "shorting" — you need to buy before you can sell. Also, you can't buy and sell in the same time step — at least 1 minute has to pass.

^{Difficulty: Easy}

^{Category: List processing, Greedy algorithms}