Leetcode: Single Number

Question

Given an array of integers, every element appears twice except for one. Find that single one.

Note:
Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?

Hide Tags Hash Table Bit Manipulation
Hide Similar Problems (M) Single Number II (M) Single Number III (M) Missing Number

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Solution 1

Get idea from here.

class Solution(object):    def singleNumber(self, nums):        """        :type nums: List[int]        :rtype: int        """        if nums==None or len(nums)==0:            return 0        res = nums[0]        for ind in range(1,len(nums)):            res ^= nums[ind]        return res

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Solution 2

Get idea from here

python