Submission #754554

#	Time	Username	Problem	Language	Result	Execution time	Memory
754554		Stickfish	Cat (info1cup19_cat)	C++17	0 / 100	32 ms	692 KiB

cat

#include <iostream>
#include <vector>
using namespace std;

void solve() {
    int n;
    cin >> n;
    vector<int> p(n);
    for (int i = 0; i < n; ++i)
        cin >> p[i], --p[i];
    for (int i = 0; i < n; ++i) if (p[i] + p[n - i - 1] != n - 1) {
        cout << "-1\n";
        return;
    }
    int e0 = 0;
    for (int i = 0; i < n / 2; ++i)
        e0 += p[i] < n / 2;
    if ((e0 + n / 2) % 2) {
        cout << "-1\n";
        return;
    }
    cout << "1\n";
    cout << "1 2\n";
}

signed main() {
    int t;
    cin >> t;
    while (t--) {
        solve();
    }
}

• Subtask 1: 0 / 15
• Subtask 2: 0 / 10
• Subtask 3: 0 / 25
• Subtask 4: 0 / 15
• Subtask 5: 0 / 35