LeetCode--No.80--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.

public class Solution {
    public int removeDuplicates(int[] nums) {
        Map<Integer, Integer> map = new HashMap<Integer, Integer>();
        int index = 0;
        for(int i = 0; i < nums.length; i++){
            if (!map.containsKey(nums[i])){
                map.put(nums[i],1);
                nums[index] = nums[i];
                index++;
            }
            else if(map.get(nums[i]) < 2){
                map.put(nums[i], map.get(nums[i])+1);
                nums[index] = nums[i];
                index++;
            }
            else{
                continue;
            }
        }
        return index;
    }
}

比较顺利。bug free。 题目简单。时间复杂度O(n).