309. Best Time to Buy and Sell Stock with Cooldown

题目

class Solution {
public:
    int maxProfit(vector<int>& prices) {
        int buy = INT_MIN;
        int pre_buy;
        int sell = 0;
        int pre_sell = 0;
        for (int i = 0; i < prices.size(); i++) {
            pre_buy = buy;
            buy = max(pre_sell - prices[i], buy);
            pre_sell = sell;
            sell = max(pre_buy + prices[i], sell);
        }
        return sell;
    }
};