leetcode80 Remove Duplicates from Sorted Array II

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

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

Your function should return length = 5, with the first five elements of nums being 1, 1, 2, 2 and 3. It doesn't matter what you leave beyond the new length.

class Solution {
public:
    int removeDuplicates(vector<int>& nums) {
        int ans=0;
        int size=nums.size();
        if(size==0)
            return 0;
        int p=0;
        
        ans++;
        p++;
        int two_flag=1;
        int cur=nums[0];
        for(int i=1;i<size;i++)
        {
            if(nums[i]==cur)
            {
                if(two_flag!=2)
                {
                    two_flag++;
                    ans++;
                    if(i!=p)
                    {
                        nums[p]=nums[i];
                    }
                    p++;
                }
            }
            else
            {
                two_flag=1;
                ans++;
                cur=nums[i];
                if(i!=p)
                {
                    nums[p]=nums[i];
                }
                p++;
            }
        }
        return ans;
    }
};