1 class Solution {
 2 public:
 3     int maxProfit(vector<int>& prices) {
 4         if (prices.size() == 0) {
 5             return 0;
 6         }
 7         int minPrice = prices[0];
 8         int result = 0;
 9         for (int i = 1; i < prices.size(); ++i) {
10             if (prices[i] < minPrice) {
11                 minPrice = prices[i];
12             }
13             else if (prices[i] > minPrice) {
14                 result = max(result,(prices[i] - minPrice));
15             }
16         }
17         return result;
18     }
19 };