136. Single Number

class Solution:
    def singleNumber(self, nums: List[int]) -> int:
        ans = nums[0]
        for num in nums[1:]:
            # XOR returns 0 when doing two of the same number
            ans ^= num
        return ans

• we use a logical xor between each of the integers, because two identical numbers, when xor’d will give 0.
• only the bits for the single number will remain.

Categories:: math, array