LeetCode Best Time to Buy and Sell Stock II

class Solution {
public:
    int maxProfit(vector<int> &prices) {
        int len = prices.size();
        if (len < 1) return 0;
        int sum = 0;
        int last_low = prices[0];

        bool increasing = false;
        for (int i=1; i<len; i++) {
            int cur = prices[i];
            if (cur < prices[i - 1]) {
                if (increasing) {
                    increasing = false;
                    sum += prices[i - 1] - last_low;
                }
                last_low = cur;
            } else {
                if (increasing) {
                    
                } else {
                    increasing = true;
                }
            }
        }
        if (increasing) {
            sum += prices[len-1] - last_low;
        }
        return sum;
    }
};

 第二轮：

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).

看看当初写的有点繁琐啊

class Solution {
public:
    int maxProfit(vector<int> &prices) {
        int len = prices.size();
        if (len < 2) return 0;
        int last = prices[0];
        int profit = 0;
        for (int i=1; i<len; i++) {
            profit += max(0, prices[i] - last);
            last = prices[i];
        }
        return profit;
    }
};