27.136. Single Number

class Solution:
    def singleNumber(self, nums: List[int]) -> int:
        res = nums[0]
        for n in nums[1:]:
            res = res^n
            
        return res

28.137. Single Number II

class Solution:
    def singleNumber(self, nums: List[int]) -> int:
        res = int((3*sum(set(nums))-sum(nums))/2)
        return res
        

class Solution:
    def singleNumber(self, nums: List[int]) -> int:
        ones = 0
        twos = 0
        for num in nums:
            ones = ones^num&(~twos)
            twos = twos^num&(~ones)
        return ones

29.260. Single Number III

class Solution:
    def singleNumber(self, nums: List[int]) -> List[int]:
        diff = 0
        for num in nums:
            diff = diff^num
        
        diff = diff&(-diff)
        res = [0,0]
        for num in nums:
            if num & diff==0:
                res[0] = res[0]^num
            else:
                res[1] =  res[1]^num
        return res