func_code_string: #include <bits/stdc++.h>   using namespace std;   const long long int INF = LLONG_MAX;   vector<long long int> v1;   vector<pair<long long int, long long int> > v2;   string s1, s2, s3;   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     long long int a, b, c, d, e, f, i, j, k, cnt1 = 0, cnt2 = 0, sum1 = 0,                                              sum2 = 0, chk1 = 0, chk2 = 0, T;     cin >> T;     while (T--) {       cnt1 = 0;       v1.clear();       cin >> a >> b;       vector<long long int> ara(b + b + 3, 0);       for (i = 0; i < a; i++) {         cin >> c;         v1.push_back(c);       }       ara[0] = a;       for (i = 0; i < a / 2; i++) {         long long int mx = max(v1[i], v1[a - i - 1]);         long long int mn = min(v1[i], v1[a - i - 1]);         ara[mn + 1]--;         ara[mx + mn]--;         ara[mx + mn + 1]++;         ara[mx + b + 1]++;       }       long long int ans = INT_MAX;       for (i = 1; i <= b + b + 2; i++) {         ara[i] += ara[i - 1];         ans = min(ara[i], ans);       }       cout << ans << endl;     }     return 0;   }   