LeetCode Best Time to Buy and Sell Stock II

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).

思路分析：这题很简单，因为对transactions次数没有限制，所以我们只需要遍历数组，把相邻两天买卖赚钱的情况全部加起来，就可以得到最大的利润。这题其实比Best Time to Buy and Sell Stock I还简单，但是如果加上交易次数限制（如至多K次交易）就比较麻烦了，需要用到局部最优和全局最优的动态规划解法。

AC Code

public class Solution {    public int maxProfit(int[] prices) {        if(prices == null || prices.length == 0){            return 0;        }        //1129        int global = 0;        for(int i = 0; i < prices.length - 1; i++){            int diff = prices[i+1] - prices[i];            if(diff > 0) global += diff;        }        return global;        //1131    }}