LeetCode 122 Best Time to Buy and Sell Stock II（股票买入卖出的最佳时间 II）

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题目描述：

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).

解题思路：举一个例子4 9 2 2 8最大利润很明显是（9-4） + （8 - 2）=11就因为这个式子让我想复杂了：

首先要找到一个极小值4，然后找到极大值9；然后找到极小值2，然后找到极大值8；balabala……其实换一种思路，

（9-4） + （8 - 2） =11这样就转外为后一个比前一个大的话就加入，中间那些不是极大，极小值的会被消去~

C++代码：

class Solution {public:    int maxProfit(vector<int>& prices) {        int length = prices.size();         //中间的值可以抵消        int num = 0;        for(int i = 1;i<length;i++)        {            if(prices[i]>prices[i-1])            {                num+=prices[i]-prices[i-1];            }        }        return num;    }};

python代码：

class Solution(object):    def maxProfit(self, prices):        """        :type prices: List[int]        :rtype: int        """        num = 0        length = len(prices)        for i in range(1,length):            if prices[i]>prices[i-1]:                num = num+prices[i]-prices[i-1]        return num

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