dp_41

121. 买卖股票的最佳时机

class Solution:def maxProfit(self, prices: List[int]) -> int:dp = [[0] * 2 for _ in range(len(prices))]dp[0][0] = -prices[0]for i in range(1, len(prices)):dp[i][0] = max(dp[i - 1][0], -prices[i])dp[i][1] = max(dp[i - 1][1], dp[i - 1][0] + prices[i])return dp[-1][1]

122. 买卖股票的最佳时机 II

class Solution:def maxProfit(self, prices: List[int]) -> int:dp = [[0] * 2 for _ in range(len(prices))]dp[0][0] = -prices[0]for i in range(1, len(prices)):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[-1][1]

123. 买卖股票的最佳时机 III

class Solution:def maxProfit(self, prices: List[int]) -> int:dp = [[0] * 5 for _ in prices]dp[0][1], dp[0][3] = -prices[0], -prices[0]for i in range(1, len(prices)):for j in range(1, 5, 2):dp[i][j] = max(dp[i - 1][j], dp[i - 1][j - 1] - prices[i])dp[i][j + 1] = max(dp[i - 1][j + 1], dp[i - 1][j] + prices[i])return dp[-1][-1]