def test_best_time_to_buy_and_sell_stocks_6():
prices = [20, 5, 100, 7, 1, 20, 100]
expected = 99
actual = max_profit(prices)
assert actual == expected
def test_best_time_to_buy_and_sell_stocks_5():
prices = [1, 2]
expected = 1
actual = max_profit(prices)
assert actual == expected
def test_best_time_to_buy_and_sell_stocks_4():
prices = [1, 2, 3, 4, 5, 6, 7]
expected = 6
actual = max_profit(prices)
assert actual == expected
def test_best_time_to_buy_and_sell_stocks_1():
prices = [7, 1, 5, 3, 6, 3]
expected = 5
actual = max_profit(prices)
assert actual == expected
def test_best_time_to_buy_and_sell_stocks_2():
prices = [7, 6, 4, 3, 1]
expected = 0
actual = max_profit(prices)
assert actual == expected