Sorting

input/code.cpp: In function 'int main()':
input/code.cpp:19:7: warning: 'pos' may be used uninitialized in this function [-Wmaybe-uninitialized]
       if (pos == n) {
       ^~

#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];
    bool ans = true;
    for (int i = 1; i <= n - 3; i++) {
      int pos;
      for (int j = i; j <= n; j++) if (a[j] == i) pos = j;
      if (pos == i) continue;
      if (pos == n) {
        if (i <= n - 4) {
          swap(a[pos - 2], a[pos]);
          swap(a[pos - 3], a[pos - 1]);
          pos -= 2;
        } else {
          ans = false;
          break;
        }
      } else if (pos == i + 1) {
        if (i <= n - 4) {
          swap(a[pos], a[pos + 2]);
          swap(a[pos + 1], a[pos + 3]);
          pos += 2;
        } else {
          ans = false;
          break;
        }
      }
      swap(a[i], a[pos]);
      swap(a[i + 1], a[pos + 1]);
    }
    for (int i = 1; i <= n; i++) if (a[i] != i) ans = false;
    if (ans) cout << "YES\n";
    else cout << "NO\n";
  }
  return 0;  
}

Test 1

Group: 1, 2

Verdict: WRONG ANSWER

Test 2

Group: 2

Verdict: WRONG ANSWER

Test 3

Group: 1, 2

Verdict: WRONG ANSWER

Test 4

Group: 1, 2

Verdict: WRONG ANSWER