20-136. Single Number
题目描述:
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
代码实现:
1 class Solution(object): 2 def singleNumber(self, nums): 3 """ 4 :type nums: List[int] 5 :rtype: int 6 """ 7 return reduce(operator.xor, nums) # method1 8 # return 2*sum(set(nums))-sum(nums) # method2 9 # return reduce(lambda x, y: x ^ y, nums) # method3