<reponame>jen-sjen/data-structures-basics-leetcode
""" 
# SINGLE NUMBER

Given a non-empty array of integers nums, every element appears twice except for one. Find that single one.

Follow up: Could you implement a solution with a linear runtime complexity and without using extra memory?

 
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. 
"""

class Solution:
    def singleNumber(self, nums) -> int:
        res = 0
        for x in nums:
            res = res ^ x
        return res