func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     int t = 1;     cin >> t;     while (t--) {       int n;       cin >> n;       vector<int> v(n);       for (int i = 0; i < n; i++) cin >> v[i];       vector<int> ans(n);       for (int i = 0; i < n / 2; i++) {         ans[i] = v[n - 1 - i];         ans[n - 1 - i] = -1 * v[i];       }       for (int ele : ans) cout << ele <<    ;       cout << endl;     }     return 0;   }   