122. Best Time to Buy and Sell Stock II

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122. Best Time to Buy and Sell Stock II

题目

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).

解析

• 主要理解思路：将所有递增的数累加即可。
• 本题由于允许多次交易（每次必须先卖出再买进），所以不好用爆搜
• 分析可知，要想利益最大化，就应该每次在波谷买进，波峰卖出，这样利益最大，操作次数最少

class Solution_122 {
public:
    int maxProfit(vector<int>& prices) {

        int max_profit = 0;
        for (int i = 1; i < prices.size();i++)
        {
            prices[i - 1] = prices[i] - prices[i - 1];
            if (prices[i-1]>0)
            {
                max_profit += prices[i - 1];
            }
        }

        return max_profit;
    }
    
};

题目来源

• 122. Best Time to Buy and Sell Stock II