class Solution:
    def singleNumber(self, nums: List[int]) -> List[int]:
        ans, a, b = 0, 0, 0
        for n in nums:
            ans ^= n
        ans = ans & (1-ans) ## find the least significant 1
        for n in nums:
            if n&ans:
                a ^= n
            else:
                b ^= n
        return [a,b]