Best Time to Buy and Sell Stock ii

Problem

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).

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Idea

相邻两个价格差一下，然后把》0的加起来。为啥？ 因为如果第二天价格低了，第二天再买就肯定能达到最大profit，所以第一天就不要了

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Solution

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