leetcode 刷题之路 72 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).

在Best Time to Buy and Sell Stock I的基础上放宽了条件，允许多次操作，但是必须在出售掉现有股票后才能买入新的股票。

为了获得最大利益，应该在价格最低时买入，最高时买入，例如，数组 2 1 3 5 4，我们应该在价格1时买入，价格5时卖出，这种情况和在价格1时买入，价格3时卖出又买入，价格5时卖出的收益是一样的。所以，我们可以这样设计算法， 只要下一天比今天股价高，就在今天买入，下一天卖出，这样获得利益最大。

AC code：

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