Sorting

#include <bits/stdc++.h>

using namespace std;

using ll = long long;

const int MAX_N = 100;
int p[1 + MAX_N];


void solveTest () {
    int n;
    cin >> n;
    for (int i = 1; i <= n; i++)
        cin >> p[i];
    if (n < 4) {
        for (int i = 1; i <= n; i++)
            if (p[i] != i) {
                cout << "NO\n";
                return;
            }
        cout << "YES\n";
    }
    if (n == 4) {
        bool ok = true;
        for (int i = 1; i <= n; i++)
            if (p[i] != i) {
                ok = false;
            }
        if (ok) {
            cout << "YES\n";
            return;
        }
        swap (p[1], p[3]);
        swap (p[2], p[4]);
        ok = true;
        for (int i = 1; i <= n; i++)
            if (p[i] != i) {
                ok = false;
            }
        if (ok) {
            cout << "YES\n";
        }
        else {
            cout << "NO\n";
        }
        return;
    }
    int inv = 0;
    for (int i = 1; i <= n; i++)
        for (int j = i + 1 ; j <= n; j++)
            if (p[i] > p[j])
                inv++;
    if (inv & 1)
        cout << "NO\n";
    else
        cout << "YES\n";
}

int main () {
    int t;
    cin >> t;
    while (t--)
        solveTest ();
    return 0;
}

Test 1

Group: 1, 2

Verdict: WRONG ANSWER

Test 2

Group: 2

Verdict: WRONG ANSWER

Test 3

Group: 1, 2

Verdict: ACCEPTED

Test 4

Group: 1, 2

Verdict: ACCEPTED