func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int t;     cin >> t;     while (t--) {       int n;       cin >> n;       n *= 2;       int arr[n];       vector<int> ans;       unordered_set<int> s;       for (int i = 0; i < n; i++) {         cin >> arr[i];         if (s.find(arr[i]) == s.end()) {           ans.push_back(arr[i]);           s.insert(arr[i]);         }       }       for (int i = 0; i < ans.size(); i++) {         cout << ans[i] <<    ;       }       cout << endl;     }   }   