题目

题解

labuladong的状态图解

class Solution:
    def maxProfit(self, prices: List[int]) -> int:
        N = len(prices)
        # 定义状态：dp[i][j]表示在第i天持有或卖出时的最大利润，j=1代表持有，j=0代表卖出
        dp = [[0 for j in range(2)] for i in range(N)]

        for i in range(N):
            # badcase
            if i - 1 == -1:
                dp[i][0] = 0
                dp[i][1] = -prices[i]
            else:
                dp[i][0] = max(dp[i-1][0], dp[i-1][1] + prices[i])
                dp[i][1] = max(dp[i-1][1], dp[i-1][0] - prices[i])
        return dp[N-1][0]