121.py

#You are given an array prices where prices[i] is the price of a given stock on the ith day.

#You want to maximize your profit by choosing a single day to buy one stock and choosing a different day in the future to sell that stock.

#Return the maximum profit you can achieve from this transaction. If you cannot achieve any profit, return 0.


class Solution:
    def maxProfit(self, prices: List[int]) -> int:
        l, r = 0, 1
        output = 0

        while r < len(prices):
            if prices[l] > prices[r]:
                l = r
                r += 1
            else:
                output = max(output, prices[r]-prices[l])
                r += 1

        return output