LeetCode - 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].

class Solution {public:    int removeDuplicates(int A[], int n) {if(n<3){return n;}int num=0,counter=0,prev=0,curr=0,tmp=0;while(tmp<n){tmp=curr;while(tmp<n&&A[tmp]==A[curr]){tmp++;counter++;}counter=min(counter,2);for(int i=0;i<counter;i++){A[prev+i]=A[curr];}prev+=counter;num+=counter;curr=tmp;counter=0;}return num;    }};