leetcode Single Number python
#question : Given an 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 """ intlen=len(nums) if intlen == 0: return -1 if intlen == 1: return nums[0] ans=nums[0] for i in range(1,intlen): ans = ans ^ nums[i] return ans