[leetcode]122. Best Time to Buy and Sell Stock II 最佳炒股时机之二

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 (i.e., buy one and sell one share of the stock multiple times).

Note: You may not engage in multiple transactions at the same time (i.e., you must sell the stock before you buy again).

Example 1:

Input: [7,1,5,3,6,4]
Output: 7
Explanation: Buy on day 2 (price = 1) and sell on day 3 (price = 5), profit = 5-1 = 4.
             Then buy on day 4 (price = 3) and sell on day 5 (price = 6), profit = 6-3 = 3.

题目

和之前一样，不过你可以买卖任意多次。

思路

相当于从专门做短线操作（short-term operation) , 只要第二天相对前一天有上涨，就transaction

if previous price > current price,   do transaction

profit += previous price - current price

代码

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