Leetcode 137. Single Number II

是136题的加强版,这次是每个数重复三次.

重复两次用一个bit记录一下,重复三次就用两个记录.很简单.

class Solution(object):
    def singleNumber(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        a,b=0,0
        for c in nums:
            a=(a^c)&~b
            b=(b^c)&~a
        return  a