122. Best Time to Buy and Sell Stock II 最佳买卖股票的时间

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).

题目解析：可以由多次交易买卖，只要最后受益最大就可以

class Solution {
public int maxProfit(int[] prices) {
if(prices==null||prices.length<=1){
return 0;
}
int profit=0;
for(int i=0;i<prices.length-1;i++){
if(prices[i+1]-prices[i]>0){
profit +=prices[i+1]-prices[i];
}
}
return profit;
}
}
解题思路：

简单来想，就是计算所有的受益，也就是计算每天能够获得的受益。如果就像题目要求的you may not engage in multiple transactions at the same time，如果这个要求是一天不能先卖出后买卖，其实也可以用如上的方法进行计算最大profit。

比如，[1，2，3]，选择1->2->3跟1->3计算结果一样.