class Solution {
    
    
public:
    int maxProfit(vector<int>& prices) {
    
    
        int n = prices.size();//天数
        vector<vector<int>> dp(n,vector<int>(3));
        dp[0][0] = -prices[0];
        for(int i = 1;i < n;++i)
        {
    
    
            dp[i][0] = max(dp[i-1][0],dp[i-1][1]-prices[i]);
            dp[i][1] = max(dp[i-1][1],dp[i-1][2]);
            dp[i][2] = dp[i-1][0]+prices[i];
        }
        return max(dp[n-1][1],dp[n-1][2]);
    }
};