个人主页：Lei宝啊 

愿所有美好如期而遇

也就有这样的状态转移方程：

•     买入：dp[i][0] = max(dp[i-1][1] - prices[i], dp[i-1][0]);
•  可买入：dp[i][1] = max(dp[i-1][1], dp[i-1][2]);
•  冷冻期：dp[i][2] = dp[i-1][0] + prices[i];

class Solution 
{
public:
    int maxProfit(vector<int>& prices) 
    {
        vector<vector<int>> dp(prices.size(), vector<int>(3));
        dp[0][0] = -prices[0];

        for(int i=1; i<prices.size(); i++)
        {
            dp[i][0] = max(dp[i-1][1] - prices[i], dp[i-1][0]);
            dp[i][1] = max(dp[i-1][1], dp[i-1][2]);
            dp[i][2] = dp[i-1][0] + prices[i];
        }

        int ret = max(dp[prices.size()-1][1], dp[prices.size()-1][2]);
        return ret;
    }
};