121. Best Time to Buy and Sell Stock

class Solution:
    def maxProfit(self, prices: List[int]) -> int:
        max_profit=0
        # profit=buytoday-cheapestsofar
        min_price=prices[0]
        for price in prices:
            min_price=min(price, min_price)
            max_profit=max(max_profit,price - min_price)
        return max_profit


        

class Solution(object):
    def maxProfit(self, prices):
        profit = 0
        buy = prices[0]
        for sell in prices[1:]:
            if sell > buy:
                profit = max(profit, sell - buy)
            else:
                buy = sell
        
        return profit