[LeetCode]Best Time to Buy and Sell Stock II

Say you have an array for which the i^th 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).

Have you been asked this question in an interview? Yes

思考：花了两分钟才明白了题意，英语捉急。。还是只能遍历一次数组，可以买卖多次。

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