Remove Duplicates from Sorted Array

use two index to compress array

public class Solution {
    public int removeDuplicates(int[] A) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        if(A == null||A.length < 1)
            return 0;
        if(A.length == 1)
            return 1;
        Arrays.sort(A);
        int slowrunner = 0;
        int fastrunner = 1;
        int tmp = 0;
        while(fastrunner < A.length)
        {
            if(A[slowrunner] == A[fastrunner])
            {
                fastrunner++;
            }
            else
            {
                A[++slowrunner] = A[fastrunner++];
            }
        }
        if(A[slowrunner] != A[fastrunner-1])
            A[++slowrunner] = A[fastrunner-1];
        return slowrunner+1;
    }
}