Single Number III — LeetCode 260 Python Solution

The problem

Given an integer array nums, in which exactly two elements appear only once and all the other elements appear exactly twice. Find the two elements that appear only once.

Example

Input

nums = [1,2,1,3,2,5]

Output

[3,5]

Explanation

[5, 3] is also a valid answer.

Python solution

class Solution:
    def singleNumber(self, nums: List[int]) -> List[int]:
        xs = reduce(xor, nums)
        a = 0
        lb = xs & -xs
        for x in nums:
            if x & lb:
                a ^= x
        b = xs ^ a
        return [a, b]

Complexity

Pattern: Bit Manipulation

Use XOR, masks and the low-bit trick to replace whole data structures with an integer. LeetCode 260. Single Number III is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Bit Manipulation.

The bit manipulation guide has the Python template for the pattern and the 194 LeetCode problems that use it.

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