Remove Duplicates from Sorted Array II <leetcode>

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].

题意：去掉一个数组中重复的数组，而且每个数可以出现两次，题比较简单，代码如下：

class Solution {
public:
    int removeDuplicates(int A[], int n) {
        if(0==n)  return 0;
        else if(1==n)  return 1;
        else if(2==n)  return 2;
       
        int count=1;
        int pre=A[0];
        for(int i=1;i<n;i++)
        {
            if(A[i]==pre)
            {
                count++;
                if(count>2)
                {
                    for(int j=i;j<n-1;j++)
                    {
                        A[j]=A[j+1];
                    }
                    A[n-1]=pre;
                    i--;
                    n--;
                }
            }
            else if(A[i]!=pre)
            {
                count=1;
                pre=A[i];
            }
        }
        return n;
    }
};