Single Number

Desicription

Given a non-empty 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?

Example 1:

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Input: [2,2,1]
Output: 1

Example 2:

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Input: [4,1,2,1,2]
Output: 4

Solution

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class Solution {
public:
int singleNumber(vector<int>& nums) {
int res = 0;
for(auto it : nums)
res ^= it;
return res;
}
};