题目描述:

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?

使用异或.

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