https://leetcode-cn.com/problems/best-time-to-buy-and-sell-stock/ (opens new window)

class Solution(object):
    def maxProfit(self, prices):
        """
        :type prices: List[int]
        :rtype: int
        """
        profit = 0
        minprice = prices[0]
        
        for i in range(1, len(prices)):
           profit = max(profit, prices[i] - minprice)
           minprice = min(minprice, prices[i])


        return profit