122. Best Time to Buy and Sell Stock II

难度: Medium

题目描述

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 sell and buy the stock multiple times on the same day, ensuring you never hold more than one share of the stock.

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.

Example 2:

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

Example 3:

Input: prices = [7,6,4,3,1]
Output: 0
Explanation: There is no way to make a positive profit, so we never buy the stock to achieve the maximum profit of 0.

 

Constraints:

• 1 <= prices.length <= 3 * 104
• 0 <= prices[i] <= 104

解题思路

代码实现

解决方案

java

class Solution {
    public int maxProfit(int[] prices) {
        int dp0 = 0;// 不持有股票的利润
        int dp1 = 0 - prices[0];// 持有股票的利润

        for (int i = 1; i < prices.length; i++) {
            dp0 = Math.max(dp0, dp1 + prices[i]);
            dp1 = Math.max(dp1, dp0 - prices[i]);
        }
        return Math.max(dp0,dp1);

    }
}