Sorting

#include <bits/stdc++.h>
using namespace std;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);  
  int t;
  cin >> t;
  while (t--) {
    int n;
    cin >> n;
    vector<int> a(n + 1);
    for (int i = 1; i <= n; i++) cin >> a[i];
    set< vector<int> > st; st.insert(a);
    queue< vector<int> > q; q.push(a);
    while (!q.empty()) {
      vector<int> b = q.front(), c = b; q.pop();
      for (int i = 1; i <= n - 3; i++) {
        for (int j = i + 2; j <= n - 1; j++) {
          swap(c[i], c[j]);
          swap(c[i + 1], c[j + 1]);
          if (!st.count(c)) {
            st.insert(c);
            q.push(c);
          }
          swap(c[i], c[j]);
          swap(c[i + 1], c[j + 1]);
        }
      }
    }
    vector<int> p(n + 1);
    iota(p.begin(), p.end(), 0);
    if (st.count(p)) cout << "YES\n";
    else cout << "NO\n";
  }
  return 0;  
}

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 2

Verdict: TIME LIMIT EXCEEDED

Test 3

Group: 1, 2

Verdict: ACCEPTED

Test 4

Group: 1, 2

Verdict: TIME LIMIT EXCEEDED