Remove Duplicates from Sorted Array II

similar with Remove Duplicates from Sorted 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)
            return 0;
        if(A.length < 3)
            return A.length;
        int slowrunner = 0;
        int fastrunner = 1;
        boolean hasDup = false;
        while(fastrunner < A.length)
        {
            if(A[slowrunner] == A[fastrunner])
            {
                if(hasDup)
                    fastrunner++;
                else{
                    A[++slowrunner] = A[fastrunner++];
                    hasDup = true;
                }
            }
            else
            {
                A[++slowrunner] = A[fastrunner++];
                hasDup = false;
            }
        }
            
        return slowrunner+1;
    }
}