LeetCode -- 122. 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).

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思路：
这道题思路比较简单，每次在股票跌之前卖出即可得到累计收益最大。注意判断边界条件，如果股票一直在涨（递增数组），那么最后一天卖出。

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C++代码如下：

class Solution {public:    int maxProfit(vector<int>& prices) {        int profit = 0;        int index = 0, len = prices.size();        if(len <= 0)            return 0;        for(int i=1; i<len; i++)        {            if(i == len-1 && prices[i]>=prices[i-1])            {                profit += prices[i]-prices[index];                break;            }            if(prices[i]<=prices[i-1])            {                profit += prices[i-1]-prices[index];                index = i;            }        }        return profit;    }};