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).

Solution 1: if the current price is higher than yesterday,  the price gap can be added to the profit.

 1 class Solution {
 2 public:
 3     int maxProfit(vector<int>& prices) {
 4         int res=0;
 5         for (int i=1;i<prices.size();i++){
 6             if (prices[i]>prices[i-1]) res+=prices[i]-prices[i-1];
 7         } 
 8         return res;
 9     }
10 };

 Solution 2: peak-valley approach: buy the valley, sell the peak, each peak-valley are added.

https://leetcode.com/articles/best-time-buy-and-sell-stock-ii/

122. Best Time to Buy and Sell Stock II