LeetCode 136. 只出现一次的数字

示例 1:

输入: [2,2,1]
输出: 1
示例 2:

输入: [4,1,2,1,2]
输出: 4

class Solution:
    def singleNumber(self, nums: [int]) -> int:
        #列表方式
        # tempList = []
        # for i in nums:
        #     if i in tempList:
        #         tempList.remove(i)
        #     else:
        #         tempList.append(i)
        # return tempList.pop()
        #字典方式
        # tempDic = {}
        # for i in nums:
        #     if i in tempDic:
        #         del tempDic[i]
        #     else:
        #         tempDic[i] = 1
        # return tempDic.popitem()[0]
        #异或
        ans = 0
        for i in nums:
            ans ^= i
        return ans