leetcode刷题笔记-bit

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136. Single Number

这题关键是最多的也只重复2次。

class Solution(object):
    def singleNumber(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        res = nums[0]
        for i in xrange(1, len(nums)):
            res ^= nums[i]

        return res

 return sum(set(nums))*2 - sum(nums)