new_contents: """
  https://leetcode.com/problems/best-time-to-buy-and-sell-stock/description/
  121. Best Time to Buy and Sell Stock
  
  Say you have an array for which the ith element is the price of a given stock on day i.
  
  If you were only permitted to complete at most one transaction (ie, buy one and sell one share of the stock), design an algorithm to find the maximum profit.
  
  Example 1:
  Input: [7, 1, 5, 3, 6, 4]
  Output: 5
  
  max. difference = 6-1 = 5 (not 7-1 = 6, as selling price needs to be larger than buying price)
  Example 2:
  Input: [7, 6, 4, 3, 1]
  Output: 0
  
  In this case, no transaction is done, i.e. max profit = 0.
  
  """
  class Solution(object):
      def maxProfit(self, prices):
          """
          :type prices: List[int]
          :rtype: int
          """
          max_profit = 0
          min_price = 10**6
          for price in prices:
              if price < min_price:
                  min_price = price
              elif price - min_price > max_profit:
                  max_profit = price - min_price
          return max_profit
              
          
  
subject: Create 121_buy_sell_stock.py