Remove Duplicates from Sorted Array II

Given an integer array nums sorted in non-decreasing order , remove some duplicates in-place such that each unique element appears at most twice . The relative order of the elements should be kept the same .

Since it is impossible to change the length of the array in some languages, you must instead have the result be placed in the first part of the array nums . More formally, if there are k elements after removing the duplicates, then the first k elements of nums should hold the final result. It does not matter what you leave beyond the first k elements.

Return k after placing the final result in the first k slots of nums .

Do not allocate extra space for another array. You must do this by modifying the input array in-place with O(1) extra memory.

Custom Judge:

The judge will test your solution with the following code:

int[] nums = [...]; // Input array

int[] expectedNums = [...]; // The expected answer with correct length

int k = removeDuplicates(nums); // Calls your implementation

assert k == expectedNums.length;

for (int i = 0; i < k; i++) {

assert nums[i] == expectedNums[i];

}

If all assertions pass, then your solution will be accepted .