[136] Single Number

https://leetcode.com/problems/single-number/description/

• algorithms
• Easy (57.71%)
• Source Code: 136.single-number.py
• Total Accepted: 443.3K
• Total Submissions: 743.3K
• Testcase Example: '[2,2,1]'

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(object):
    def singleNumber(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        return reduce(lambda x, y: x ^ y, nums)