class Solution:
    def maxProfit(self, prices: List[int]) -> int:
        max_profit = 0
        buy_index = 0
        if len(prices) == 1:
            return 0
        for i, cur_price in enumerate(prices):
            profit = cur_price - prices[buy_index]
            if profit > max_profit:
                max_profit = profit
            elif cur_price < prices[buy_index]:
                buy_index = i

        return max_profit