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.

Related issue: 26 Remove Duplicates from Sorted Array

public class Solution {
    public int removeDuplicates(int[] nums) {
        int i=0;
        int j=1;
        boolean allowDup = true;
        for(;j<nums.length;){
            if(nums[i] == nums[j]){
                if(allowDup){
                    allowDup = false;
                    nums[++i] = nums[j++];
                }else{
                    j++;
                }
            }else{
                allowDup = true;
                nums[++i] = nums[j++];
            }
        }

        return ++i;
    }
}

slightly simpler code.

public class Solution {
    public int removeDuplicates(int[] nums) {
        if(nums == null) return 0;
        if(nums.length <= 2) return nums.length;
        boolean allow = true;
        int l = 0;
        for(int r=1; r<nums.length; r++){
            if(nums[r] == nums[l]){
                if(allow){
                    nums[++l] = nums[r];
                    allow = false;
                }
            }else{// not equal case.
                allow = true;
                nums[++l] = nums[r];
            }
        }
        return l+1;
    }
}

public class Solution {
    public int removeDuplicates(int[] nums) {
        if(nums == null) return 0;
        if(nums.length <= 2) return nums.length;

        boolean allow = true;

        int k = 0;
        for(int i =1 ; i< nums.length; i++){

            if(nums[i] != nums[k] || allow){
                nums[++k] = nums[i];
                allow = nums[i] != nums[k-1] ? true : false;

            }
        }
        return ++k;
    }
}