题解 | #只出现一次的牛II#

class Solution {
public:
//使用哈希表统计出现的次数，如果为1则push_back
   vector<int> findSingleCowsII(vector<int> &nums)
    {
        std::unordered_map<int, int> count;
        vector<int> result;

        for (auto &num : nums)
        {
            count[num]++;
        }

        for (auto &single_val : count)
        {
            if (single_val.second == 1)
            {
                result.push_back(single_val.first);
            }
        }
        std::sort(result.begin(), result.end());
        return result;
    }
};