【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 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) {
        if(nums.size()==0||nums.size()==1) return nums.size();
        int dup=1;
        int index=1;
        for(int i=1;i<nums.size();i++)
        {
            if(nums[i]==nums[i-1])
                dup++;
            else
                dup=1;

            nums[index]=nums[i];
            if(dup<=2)
                index++;
        }
        return index;
    }
};