removeDup2.java

/*
Follow up for "Remove Duplicates":
What if duplicates are allowed at most twice?

For example,
Given sorted array A = [1,1,1,2,2,3],

Your function should return length = 5, and A is now [1,1,2,2,3].
*/

public class Solution {
    public int removeDuplicates(int[] A) {
        // Start typing your Java solution below
        // DO NOT write main() function
        int size = A.length;
        if (size <= 1)
            return size;
        int fast = 1;
        int slow = 0;
        int dup = 0;
        while ( fast < size) {
            if (A[slow] != A[fast]) {
                A[slow+1] = A[fast];
                slow++;
                dup = 0;
            } else{
                dup++;
                if (dup < 2) {
                    A[slow+1] = A[fast];
                    slow++;
                }
            }
            fast++;
        }
        return slow+1;
    }
}