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

Note:

Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?

Example 1:

Input: [2,2,1]

Output: 1

Example 2:

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

Output: 4

class Solution:

    def singleNumber(self, nums):

        """

        :type nums: List[int]

        :rtype: int

        """

        nums.sort()

        n=len(nums)

        i=0

        while i!=n:

            if i==n-1 or nums[i]!=nums[i+1]:

                return nums[i]

            i+=2