​​nums​​, in which exactly two elements appear only once and all the other elements appear exactly twice. Find the two elements that appear only once.

For example:

​​nums = [1, 2, 1, 3, 2, 5]​​, return ​​[3, 5]​​.

Note:

  1. The order of the result is not important. So in the above example, 

​​[5, 3]​​

  1. Your algorithm should run in linear runtime complexity. Could you implement it using only constant space complexity?

1.先异或，得到的值是两个只出现一次的整数的异或值。


2.找出该异或值中第一个不为0的位置，即两个整数不相等的位。


3.根据该位将整数划分为两部分，两个整数分别位于两个部分。异或即可分别得到两个整数。




class Solution {
public:
  vector<int> singleNumber(vector<int>& nums) {
    int xres = nums[0];
    for (int i = 1; i < nums.size(); i++){
      xres ^= nums[i];
    }
    int iOne = 0;
    for (int i = 0; i < 32; i++){
      if ((xres >> i) & 1){
        iOne = i;
        break;
      }
    }
    int res1 = 0, res2 = 0;
    for (int i = 0; i < nums.size(); i++){
      if ((nums[i] >> iOne) & 1){
        res1 ^= nums[i];
      }
      else{
        res2 ^= nums[i];
      }
    }
    vector<int> res;
    res.push_back(res1);
    res.push_back(res2);
    return res;
  }
};