136 - Single Number.py

# Given a non-empty array of integers nums, every element appears twice except for one. 
# #Find that single one.
#You must implement a solution with a linear runtime complexity and use only constant extra space.


class Solution:
    def singleNumber(self, nums: list[int]) -> int:
        other = []
        for i in nums:
            if i not in other:
                other.append(i)
            else:
                other.remove(i)
        return other[0]