Create 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).

主要是建立模型，如果下跌就每次买最低点，如果上涨则卖出，并在该点买入。持平也将买点设为该点。。。。
综述就是，每个时间节点都设置为买点，遇到下个节点高就买就卖。否则只设置为买点。