Remove Duplicates from Sorted Array

use two index to compress 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||A.length < 1)
 6             return 0;
 7         if(A.length == 1)
 8             return 1;
 9         Arrays.sort(A);
10         int slowrunner = 0;
11         int fastrunner = 1;
12         int tmp = 0;
13         while(fastrunner < A.length)
14         {
15             if(A[slowrunner] == A[fastrunner])
16             {
17                 fastrunner++;
18             }
19             else
20             {
21                 A[++slowrunner] = A[fastrunner++];
22             }
23         }
24         if(A[slowrunner] != A[fastrunner-1])
25             A[++slowrunner] = A[fastrunner-1];
26         return slowrunner+1;
27     }
28 }