LeetCode 136: 只出现一次的数字

[guodongxiaren]

https://leetcode-cn.com/problems/single-number/

太简单了。不要用map。O(1)空间全员异或！

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