** Update: This was a typo on my part, but I was struggling with the issue all morning. Sometimes something this obvious can elude you even if it is right in your face.

I have solved a question on LeetCode and I was trying to run the same solution that I had developed for the problem locally. I see a weird issue where LeetCode runs my solution perfectly and all my test cases pass but when I run the same solution, just slightly modified to give inputs and display results in the command line I do not get the same output.

After debugging I see that the "not in" part of the if statement is not working the same as the LeetCode website. I would appreciate an explanation of this issue since I usually code LeetCode problems locally and I am not sure what is causing this issue.

Python version: Python 3.11.5

PC: Windows 11

LeetCode Solution:

class Solution:
    def findDifference(self, nums1: List[int], nums2: List[int]) -> List[List[int]]:
        nums1 = set(nums1)
        nums2 = set(nums2)
        tmp1 = []
        tmp2 = []

        for i in nums1:
            if i not in nums2:
                tmp1.append(i)

        for i in nums2:
            if i not in nums1:
                tmp2.append(i)
                
        return [tmp1, tmp2]

Output: [[1,3],[4,6]]

Local Solution:

class Solution:
    def findDifference(self, nums1, nums2):
        nums1 = set(nums1)
        nums2 = set(nums2)
        tmp1 = []
        tmp2 = []

        for i in nums1:
            if i not in nums2:
                tmp1.append(i)

        for i in nums2:
            if i not in nums1:
                tmp2.append(i)

        return [tmp1, tmp2]


nums1 = [1,2,3]
nums2 = [2,4,6]
execute = Solution()
print(execute.findDifference(nums1, nums1))

Output: [[], []]

Thanks for your response in advance.

>Solution :

You have a typo in your print statement, both parameters are nums1:

      print(execute.findDifference(nums1, nums1))

It should be:

      print(execute.findDifference(nums1, nums2))