Leetcode 0136 Single Number

Problem statement

https://leetcode.com/problems/single-number/

Solution

There is straightforward hash-table solution with O(n) memory and time. We can also use bit manipulation trick to evaluate XOR of all numbers, which is what we need.

Complexity

Time is O(n), space is O(1).

Code

class Solution:
    def singleNumber(self, nums):
        return reduce(xor, nums)