121. Best Time to Buy and Sell Stock

class Solution:
    def maxProfit(self, prices: List[int]) -> int:
        if len(prices) <= 1:
            return 0

        i, j = 0, 1
        maxPrice = 0

        while j < len(prices):
            maxPrice = max(maxPrice, prices[j] - prices[i])

            if prices[j] < prices[i]:
                i = j
            
            j += 1
        
        return maxPrice