题解 | 针对任意次买卖的方法

#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 两次交易所能获得的最大收益
# @param prices int整型一维数组 股票每一天的价格
# @return int整型
#


class Solution:
    def maxProfit(self , prices: List[int]) -> int:
        # write code here
        n = len(prices)
        if n<2:
            return 0
        m = 2*2+1 #2乘以买卖次数+1
        dp =[[0]*m for _ in range(n)]
        for i in range(m):
            if i%2==1:
               dp[0][i]=-prices[0]
        for i in range(1,n):
            for  j in range(1,m):
                if j%2==1:
                    dp[i][j] = max(dp[i-1][j],dp[i][j-1]-prices[i])
                else:
                    dp[i][j] = max(dp[i-1][j],dp[i][j-1]+prices[i])
        return dp[-1][-1]