from typing import List

class Solution:
    def remove(self, nums: List[int]) -> int:
        if len(nums) <= 2:
            return len(nums)

        slow = 2  # 從第三個位置開始檢查

        for fast in range(2, len(nums)):
            # 如果當前元素不等于slow指針前兩個位置的元素
            # 說明可以保留當前元素
            if nums[fast] != nums[slow - 2]:
                nums[slow] = nums[fast]
                slow += 1

        return slow

    def removeDuplicates(self, nums: List[int]) -> int:
        if not nums:
            return 0
        beginIndex = 0
        endIndex = 0
        value = nums[beginIndex]
        while endIndex < len(nums):
            if nums[endIndex] == value:
                endIndex += 1
            else:
                if endIndex - beginIndex > 2:
                    for i in range(endIndex-1, beginIndex+1, -1):
                        nums.pop(i)
                    beginIndex = beginIndex + 2
                    endIndex = beginIndex
                    value = nums[beginIndex]
                else:
                    beginIndex = endIndex
                    value = nums[beginIndex]

        if endIndex - beginIndex > 2:
            for i in range(endIndex-1, beginIndex+1, -1):
                nums.pop(i)
        return len(nums)

if __name__ == '__main__':
    #print(Solution().removeDuplicates([1,1,1]))
    #print(Solution().removeDuplicates([1,1,1,2,2,3]))
    print(Solution().removeDuplicates([0,0,1,1,1,1,2,3,3]))