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].

https://oj.leetcode.com/problems/remove-duplicates-from-sorted-array-ii/