leetcode 122. Best Time to Buy and Sell Stock II

Best Time to Buy and Sell Stock II

unlocked question, 所以不贴截图了

This solution is really smart. 当后一个比前一个大的时候，把差值加入result中。 e.g.: ｛7, 1, 2, 5, 4, 3｝，7, 1递减，不对result操作。 1，2，5递增，5 - 1 = (2 - 1) + (5 - 2)， 把(2 - 1) and (5 - 2)分别加入result。

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