Remove Duplicates from Sorted Array python

Given an integer array nums sorted in non-decreasing order, remove the duplicates in-place such that each unique element appears only once. The relative order of the elements should be kept the same. Then return the number of unique elements in nums.

Consider the number of unique elements of nums to be k, to get accepted, you need to do the following things:

• Change the array nums such that the first k elements of nums contain the unique elements in the order they were present in nums initially. The remaining elements of nums are not important as well as the size of nums.
• Return k.

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.

 

Example 1:

Input: nums = [1,1,2]
Output: 2, nums = [1,2,_]
Explanation: Your function should return k = 2, with the first two elements of nums being 1 and 2 respectively.
It does not matter what you leave beyond the returned k (hence they are underscores).

Example 2:

Input: nums = [0,0,1,1,1,2,2,3,3,4]
Output: 5, nums = [0,1,2,3,4,_,_,_,_,_]
Explanation: Your function should return k = 5, with the first five elements of nums being 0, 1, 2, 3, and 4 respectively.
It does not matter what you leave beyond the returned k (hence they are underscores).

 

Constraints:

• 1 <= nums.length <= 3 * 104
• -100 <= nums[i] <= 100
• nums is sorted in non-decreasing order.

 

class Solution:
    def removeDuplicates(self, nums: List[int]) -> int:
        result_set = []
        for num in nums:
            if num not in result_set:
                result_set.append(num)
        
        for i in range(len(result_set)):
            nums[i] = result_set[i]
        
        nums = nums[:len(result_set)]
        
        return len(result_set)

속도가 아주 떨어집니다.

 

이 문제를 해결하기 위해 인터넷을 찾아보니 투포인터 문제였습니다.

https://velog.io/@kgh732/Python-%EC%9C%BC%EB%A1%9C-%ED%91%B8%EB%8A%94-Leetcode26.-Remove-Duplicates-from-Sorted-Array

[Python 으로 푸는 Leetcode]26. Remove Duplicates from Sorted Array

시간이 더 단축된 것을 확인할 수 있습니다.(대략 20ms 정도)