位运算取第一个非0的位 r & (~(r-1))

class Solution(object):
    def singleNumber(self, nums):
        """
        :type nums: List[int]
        :rtype: List[int]
[1,1,2]=>1 xor 1 xor 2=2
[1, 2, 1, 3, 2, 5]=> all xor= 3 & 5 != 0 => 0x11 xor 0x101=bit 2,3 is not equal=>find bit2 and seperate like [1,1,2]
        """
        r = 0
        for num in nums:
            r = r ^ num
        assert r != 0
        n = r & (~(r-1))
        ans1, ans2 = 0, 0
        for num in nums:
            if num & n == 0:
                ans1 = ans1 ^ num
            else:
                ans2 = ans2 ^ num
        return ans1, ans2