[Top Interview 150 - Array / String] 80. Remove Duplicates from Sorted Array II

[Q] [Medium]

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.

 

• 이제부터는 귀찮아서 리스트에 '_' 추가해주는 코드는 안 하기로 했다.
• nums.count() 함수로 개수 찾아주면 끝!

# Answer

class Solution(object):
    def removeDuplicates(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        
        # remove duplicates
        cnt = 1
        for _ in range(1, len(nums)):
            if nums.count(nums[cnt]) >= 3:
                del nums[cnt]
                cnt -= 1
            cnt += 1

        # k
        k = len(nums)
        
        return k