LeetCode 136. Single Number C++

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





巧用位操作
0 ^ n = n
n ^ n = 0
因为题目说明只有一个数出现一次，其余都出现两次，出现两次的数异或以后为0，0与出现一次的数n异或为n

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