class Solution {
public:
    vector<int> findNumsAppearOnce(vector<int>& nums) {
        int n = nums.size();
        unordered_map<int, int> hash;
        vector<int> ans;
        for(int i = 0; i < n; i++){
            hash[nums[i]]++;
        }
        for(int i = 0; i < n; i++){
            if(hash[nums[i]] == 1){
                ans.push_back(nums[i]);
            }
        }
        return ans;
    }
};