1 int maxProfit(vector<int> &prices) { 2         if (prices.empty())  3             return 0; 4          5         int profit = 0; 6         int climax = prices[prices.size() - 1]; 7          8         for (int i = prices.size() - 2; i >= 0; i--) { 9             if (prices[i] >= prices[i + 1]) {10                 profit += climax - prices[i + 1];11                 climax = prices[i];12             }13         }14         profit += climax - prices[0];15         16         return profit;17 }