Stay button --single number (a number appears only) python achieve

Subject description:

Chinese:

Given a non-empty array of integers, in addition to an element appears only once, the rest of each element appears twice. To find out that only appears once in the elements.

Description:

Your algorithm should have linear time complexity. You can not use the extra space to achieve it?

English:

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?

class Solution(object):
    def singleNumber(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        return 2*sum(set(nums)) - sum(nums)

 

 

Topic Source: stay button