[LeetCode&Python] Problem 136. Single Number

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