题目

Given an array of integers, every element appears twice except for one. Find that single one.

思路

两个相同的数字异或为零

代码

class Solution(object):
    def singleNumber(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        if nums==None or len(nums)==0:
            return None
        res = 0
        for num in nums:
            res ^= num
        return res