122. 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).

解答：
想清楚了其实很简单。只要买的日期比卖的日期早就可以，可以当天卖了再买回来；当天买再卖就没意思了。
三种情况：
3 4 5： 第一天买，第三天卖 = 第一天买，第二天卖，第二天买，第三天卖。
3 6 5：第一天买，第二天卖
3 2 5：第一天买，第三天卖

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