1 public class Solution {
 2     public int maxProfit(int[] prices) {
 3         if (prices == null) {
 4             return 0;
 5         }
 6         
 7         int maxProfit = 0;
 8         int minValue = Integer.MAX_VALUE;
 9         
10         for (int i: prices) {
11             minValue = Math.min(minValue, i);
12             maxProfit = Math.max(maxProfit, i - minValue);
13         }
14         
15         return maxProfit;
16     }
17 }