Problem¶

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

On each day, you may decide to buy and/or sell the stock. You can only hold at most one share of the stock at any time. However, you can buy it then immediately sell it on the same day.

Find and return the maximum profit you can achieve.

Example 1:

**Input:** prices = [7,1,5,3,6,4]
**Output:** 7
**Explanation:** Buy on day 2 (price = 1) and sell on day 3 (price = 5), profit = 5-1 = 4.
Then buy on day 4 (price = 3) and sell on day 5 (price = 6), profit = 6-3 = 3.
Total profit is 4 + 3 = 7.

Solve¶

Dynamic programing python¶

• I already solve 714. Best Time to Buy and Sell Stock with Transaction Fee, and it quite the same.

• Here is quick modified to get the right answer. Which just reduce the fee part
  

  class Solution:
      def maxProfit(self, prices: List[int]) -> int:
          bestProfit = [0, 0]
          for step, price in enumerate(prices):
              if step == 0:
                  bestProfit[1] = - price
                  continue
              tmp = bestProfit[0]
              bestProfit[0] = max(bestProfit[0], bestProfit[1] + price)
              bestProfit[1] = max(bestProfit[1], tmp - price)
          return bestProfit[0]