leetcode Question 78: Remove Duplicates from Sorted Array II

Remove Duplicates from Sorted Array II

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].

Analysis:
Just like the idea of previous problem (see Remove Duplicates from Sorted Array)
But add another flag store the number of duplicated elements.
Details can be seen in code.

Code:

class Solution {
public:
    int removeDuplicates(int A[], int n) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if (n==0){return 0;}
        if (n==1){return A[0];}
        int pre=A[0];
        int pos = 0;
        int m=n;
        int i=1;
        int count =0;
        while (i<m){
            if (A[i]==pre){
                count ++;
                if (count <2){
                    i++;
                }else{
                    m=m-1;
                    for (int j=pos+1; j<m;j++){
                        A[j]=A[j+1];
                    }
                }
            }else{
                count =0;
                pre=A[i];
                pos=i;
                i++;
            }        
        }
        return m;
    }
};