Single Number

Problem: Single Number

This problem is a easier version of Single Number II. We simply use bit manipulation exclusive-or on all the numbers we have. By this operation, we can make reduce same numbers to 0, then what's left is the single number.

Code in Python:

class Solution(object):
    def singleNumber(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        res = 0
        for x in nums:
            res ^= x
        return res