136. Single Number(位运算)

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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:

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

Example 2:

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

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class Solution {
public:
    int singleNumber(vector<int>& nums) {
        int a = nums[0];
        for(int i = 1; i < nums.size();i++)
            a^=nums[i];
        return a;
    }
};