LeetCode 122. Best Time to Buy and Sell Stock II

原题链接在这里：https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/

题目：

Say you have an array for which the ith element is the price of a given stock on day i.

Design an algorithm to find the maximum profit. You may complete as many transactions as you like (ie, buy one and sell one share of the stock multiple times). However, you may not engage in multiple transactions at the same time (ie, you must sell the stock before you buy again). 

题解：

这里可以进行无数次交易，当然不能比prices.length - 1还多，就是每次股票比前一天差价大于0都进行交易，把这些大于0的差价相加就是最后返回的结果。

Time Complexity: O(prices.length).

Space: O(1).

AC Java:

public class Solution {
    public int maxProfit(int[] prices) {
        if(prices == null || prices.length <= 1){
            return 0;
        }
        int res = 0;
        for(int i = 1; i<prices.length; i++){
            res+=Math.max(prices[i]-prices[i-1],0);
        }
        return res;
    }
}

是Best Time to Buy and Sell Stock的进阶版，但思路去不同.