LeetCode 136. Single Number （算法、异或）

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?

输入一组整数如[1,1,2,3,3]，几乎所有数都出现两次，只有一个数出现一次，找出这个数。

思路：异或。A xor A = 0， A xor B xor A = B

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