27.leetcode136_single_number

1.题目描述

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?

在给定数组中除了一个元素外每个元素出现两次，找到那个孤独的元素（注意：在线性时间内解决，而且不使用额外空间）

2.题目分析

典型的位运算，异或操作，遇到相同的数结果为0

3.解题思路

class Solution(object):
    def singleNumber(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        result=0  
        i=0
        while i<len(nums):
            result ^= nums[i] #异或操作
            i+=1
        return result