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;
    }
};