数组中只出现一次的数字

#include <iostream>
#include <vector>
#include <map>
using namespace std;
// 利用map  时间复杂度O(n), 空间复杂度不是O(1)，所以可以优化
class Solution {
public:
void FindNumsAppearOnce(vector<int> data,int* num1,int *num2) {
    int len = data.size();
    if (len < 2)
        return ;
    map<int, int> map1;
    for(int i = 0; i < data.size(); i++)
    {
        map1[data[i]]++;
    }

    int flag = 0;
    for(auto it = map1.begin(); it != map1.end(); it++)
    {
        if (it->second == 1)
        {
            if (flag == 0)
            {
               *num1 = (it->first);
               flag = 1;
            }
            else
                *num2 = (it->first);
        }
    }
}
};
int main()
{
    Solution s;
    vector<int> vec = {1,2,2,7,3,3,6,6};
    int a = 0, b= 0;
    s.FindNumsAppearOnce(vec, &a, &b);
    cout << a << " "<< b;
    return 0;
}