[LeetCode] 136. Single Number

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


参考 https://github.com/grandyang/leetcode/issues/136

class Solution {
public:
    int singleNumber(vector<int>& nums) {
        // 异或 想法（来源于位操作）
        int res = 0;
        for (auto& num : nums) {
            res = res ^ num;
        }
        return res;
    }
};