Remove Duplicates from Sorted Array II

similar with Remove Duplicates from Sorted Array
 1 public class Solution {
 2     public int removeDuplicates(int[] A) {
 3         // IMPORTANT: Please reset any member data you declared, as
 4         // the same Solution instance will be reused for each test case.
 5         if(A == null)
 6             return 0;
 7         if(A.length < 3)
 8             return A.length;
 9         int slowrunner = 0;
10         int fastrunner = 1;
11         boolean hasDup = false;
12         while(fastrunner < A.length)
13         {
14             if(A[slowrunner] == A[fastrunner])
15             {
16                 if(hasDup)
17                     fastrunner++;
18                 else{
19                     A[++slowrunner] = A[fastrunner++];
20                     hasDup = true;
21                 }
22             }
23             else
24             {
25                 A[++slowrunner] = A[fastrunner++];
26                 hasDup = false;
27             }
28         }
29             
30         return slowrunner+1;
31     }
32 }