309.Best Time to Buy and Sell Stock with Cooldown

tags: Medium,Array,DP

309. Best Time to Buy and Sell Stock with Cooldown

題目描述

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

Find the maximum profit you can achieve. You may complete as many transactions as you like (i.e., buy one and sell one share of the stock multiple times) with the following restrictions:

• After you sell your stock, you cannot buy stock on the next day (i.e., cooldown one day).

Note: You may not engage in multiple transactions simultaneously (i.e., you must sell the stock before you buy again).

範例

Example 1:

Input: prices = [1,2,3,0,2]
Output: 3
Explanation: transactions = [buy, sell, cooldown, buy, sell]

Example 2:

Input: prices = [1]
Output: 0

Constraints:

• 1 <= prices.length <= 5000
• 0 <= prices[i] <= 1000

解答

C++

class Solution {
public:
    int maxProfit(vector<int>& prices) {
        int buy = INT_MIN, hold = INT_MIN, sell = 0, cooldown = 0;
        for (auto price : prices) {
            hold = max(hold, buy);
            buy = cooldown - price;
            cooldown = max(sell, cooldown);
            sell = hold + price;
        }
        return max(cooldown, sell);
    }
};

Yen-Chi ChenFri, Dec 23, 2022

Python

class Solution:
    def maxProfit(self, prices: List[int]) -> int:
        buy, hold, sell, cooldown = -math.inf, -math.inf, 0, 0
        for price in prices:
            hold = max(hold, buy)
            buy = cooldown - price
            cooldown = max(cooldown, sell)
            sell = hold + price
        return max(sell, cooldown)

Yen-Chi ChenFri, Dec 23, 2022

三個狀態的做法

class Solution:
    def maxProfit(self, prices: List[int]) -> int:
        hold, sold, rest = -math.inf, 0, 0
        for price in prices:
            hold, sold, rest = max(hold, rest - price), hold + price, max(rest, sold)
        return max(sold, rest)

Yen-Chi ChenMon, Dec 26

Reference

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