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.

Example 1:

Input: nums = [2,2,1]

Output: 1

Example 2:

Input: nums = [4,1,2,1,2]

Output: 4

Example 3:

Input: nums = [1]

Output: 1

Constraints:

• 1 <= nums.length <= 3 * 104
• -3 * 104 <= nums[i] <= 3 * 104
• Each element in the array appears twice except for one element which appears only once.'

Approach

• Take XOR of all the numbers

class Solution:
    def singleNumber(self, nums: List[int]) -> int:
        xor = nums[0]
        for i in range(1,len(nums)):
            xor =  nums[i] ^ xor
        return xor