Sorting

input/code.cpp: In function 'int main()':
input/code.cpp:34:16: warning: unused variable 'arr' [-Wunused-variable]
     int tc, n, arr[101];
                ^~~

#include <bits/stdc++.h>

using namespace std;

#define rep(i, a, b) for (int i = a; i < (b); ++i)
#define per(i, a, b) for (int i = a - 1; i >= (b); --i)
#define trav(a, x) for (auto &a : x)

#define all(x) x.begin(), x.end()
#define sz(x) x.size()
#define pb push_back

#define umap unordered_map
#define uset unordered_set
#define INF 1000000000

typedef pair<int, int> ii;
typedef pair<int, ii> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef long long ll;

#include <bits/extc++.h>
using namespace __gnu_pbds;
typedef tree<int, null_type, less<int>, rb_tree_tag,
             tree_order_statistics_node_update>
    ost;

int main() {
    ios::sync_with_stdio(0);
    cin.tie(NULL);

    ost tree;
    int tc, n, arr[101];
    cin >> tc;
    while (tc--) {
        string ans = "NO";
        int inversions = 0, num;
        cin >> n;
        rep(i, 0, n) {
            cin >> num;
            tree.insert(num - 1);
        }
        rep(i, 0, n) {
            inversions += abs(i - int(tree.order_of_key(i)) - 1);
            tree.erase(i);
        }
        if (inversions % 2) ans = "YES";
        cout << ans << '\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