Best Time to Buy and Sell Stock

class Solution:
    def maxProfitBruteForce(self, prices: List[int]) -> int:
                # This is the bad n log n solution. See the O(n) solution below.
        max_profit = 0
        for i in range(0, len(prices)-1):
            buy_price = prices[i]
            for j in range(i+1, len(prices)):
                sell_price = prices[j]
                profit = sell_price - buy_price
                if profit > max_profit:
                    max_profit = profit

        return max_profit


    def maxProfitRev(self, prices: List[int]) -> int:
        maxVal = prices[-1]
        maxProfit = 0
        for i in range(len(prices) - 1, -1, -1):
            if prices[i] > maxVal:
                maxVal = prices[i]

            else:
                profit = maxVal - prices[i]
                if profit > maxProfit:
                    maxProfit = profit
        return maxProfit

    def maxProfit(self, prices: List[int]) -> int:
        # return self.maxProfitBruteForce(prices)
        return self.maxProfitRev(prices)