#include <iostream>
#include <vector>
using namespace std;
vector<pair<int, int>> sort_ops(vector<int> p) {
int n = p.size();
vector<int> rp(n);
for (int i = 0; i < n; ++i)
rp[p[i]] = i;
vector<pair<int, int>> ans;
for (int t = 0; t < n; ++t) {
if (p[t] == t)
continue;
int i = rp[t];
ans.push_back({t, i});
swap(p[i], p[t]);
rp[p[t]] = t;
rp[p[i]] = i;
}
return ans;
}
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 e1 = 0;
for (int i = 0; i < n / 2; ++i)
e1 += p[i] >= n / 2;
if (e1 % 2) {
cout << "-1\n";
return;
}
if (e1 == 0) {
vector<int> p0(n / 2);
for (int i = 0; i < n / 2; ++i)
p0[i] = p[i];
vector<pair<int, int>> ans = sort_ops(p0);
cout << ans.size() << ' ' << ans.size() << '\n';
for (auto x : ans)
cout << x.first + 1 << ' ' << x.second + 1 << '\n';
return;
}
cout << "1 1\n";
cout << "1 2\n";
}
signed main() {
int t;
cin >> t;
while (t--) {
solve();
}
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
9 ms |
212 KB |
Correctly distinguished between possibility and impossibility |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
44 ms |
488 KB |
Output is correct |
2 |
Correct |
41 ms |
472 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
9 ms |
212 KB |
Correctly distinguished between possibility and impossibility |
2 |
Correct |
44 ms |
488 KB |
Output is correct |
3 |
Correct |
41 ms |
472 KB |
Output is correct |
4 |
Correct |
32 ms |
212 KB |
Correctly distinguished between possibility and impossibility |
5 |
Correct |
13 ms |
212 KB |
Correctly distinguished between possibility and impossibility |
6 |
Correct |
12 ms |
212 KB |
Correctly distinguished between possibility and impossibility |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
44 ms |
488 KB |
Output is correct |
2 |
Correct |
41 ms |
472 KB |
Output is correct |
3 |
Correct |
877 ms |
14692 KB |
Output is correct |
4 |
Correct |
876 ms |
15364 KB |
Output is correct |
5 |
Correct |
901 ms |
17064 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
9 ms |
212 KB |
Correctly distinguished between possibility and impossibility |
2 |
Correct |
44 ms |
488 KB |
Output is correct |
3 |
Correct |
41 ms |
472 KB |
Output is correct |
4 |
Correct |
32 ms |
212 KB |
Correctly distinguished between possibility and impossibility |
5 |
Correct |
13 ms |
212 KB |
Correctly distinguished between possibility and impossibility |
6 |
Correct |
12 ms |
212 KB |
Correctly distinguished between possibility and impossibility |
7 |
Correct |
877 ms |
14692 KB |
Output is correct |
8 |
Correct |
876 ms |
15364 KB |
Output is correct |
9 |
Correct |
901 ms |
17064 KB |
Output is correct |
10 |
Correct |
640 ms |
3944 KB |
Correctly distinguished between possibility and impossibility |
11 |
Correct |
633 ms |
3896 KB |
Correctly distinguished between possibility and impossibility |
12 |
Correct |
880 ms |
4688 KB |
Correctly distinguished between possibility and impossibility |
13 |
Correct |
761 ms |
4752 KB |
Correctly distinguished between possibility and impossibility |
14 |
Correct |
676 ms |
4488 KB |
Correctly distinguished between possibility and impossibility |