LeetCode 122 Best Time to Buy and Sell Stock II (贪心)

Say you have an array for which the i^th element is the price of a given stock on dayi.

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).

题目链接：https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/

题目分析：后面比前面大就直接减然后累加答案即可，在全升序的情况下比如2 4 6，4-2+6-4=6-2，全降序显然不买不卖，先降后升4 2 6，6-2>6-4，先升后降2 6 4，6-2>4-2，所以不管什么情况，只要后一个比当前的大，累加这段的贡献值必然能达到全局最优的状态。

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