#define wiwihorz
#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma loop-opt(on)
#define rep(i, a, b) for(int i = a; i <= b; i ++)
#define rrep(i, a, b) for(int i = b; i >= a; i--)
#define all(x) x.begin(), x.end()
#define ceil(a, b) ((a + b - 1) / (b))
using namespace std;
#define int long long int
#define lld long double
#define pii pair<int, int>
#define random mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count())
#ifdef wiwihorz
#define print(a...) cerr << "Line: " << __LINE__, kout("[" + string(#a) + "] = ", a)
void vprint(auto L, auto R) { while(L < R)cerr << *L << " \n"[next(L) == R], ++L; }
void kout() { cerr << endl; }
template<class T1, class ... T2> void kout(T1 a, T2 ... e) { cerr << a << " ", kout(e...);}
#else
#define print(...) 0
#define vprint(...) 0
#endif
namespace solver {
int n;
vector<int> a, b, vis, top, inv;
vector<pii> ans;
void init_(int _n) {
n = _n;
a.assign(n + 1, 0);
b.assign(n + 1, 0);
vis.assign(n + 1, -1);
top.assign(n + 1, 0);
inv.assign(n + 1, 0);
ans.clear();
}
void dfs(int x) {
vis[x] = 0;
if(!b[x]) {
if(vis[a[x]] == -1) dfs(a[x]);
top[x] = top[a[x]], top[a[x]] = 0;
}
else top[x] = x;
}
void solve() {
int cnt = 0;
rep(i, 1, n / 2) {
if(a[i] + a[n - i + 1] != n + 1) {
cout << "-1\n";
return;
}
if(a[i] > n / 2) {
b[i] = 1, cnt++;
swap(a[i], a[n - i + 1]);
}
}
if(cnt & 1) {
cout << "-1\n";
return;
}
rep(i, 1, n / 2) {
inv[a[i]] = i;
if(vis[i] == -1) dfs(i);
}
rep(i, 1, n / 2) if(top[i] && b[top[i]]) {
// print(i, top[i]);
if(a[top[i]] != i && b[inv[i]]) {
b[top[i]] = 0, b[inv[i]] = 0;
ans.push_back({top[i], n - inv[i] + 1});
swap(a[top[i]], a[inv[i]]);
swap(a[n - top[i] + 1], a[n - inv[i] + 1]);
}
}
vector<int> temp;
rep(i, 1, n / 2) if(b[i]) {
assert(top[a[i]] == i);
temp.push_back(i);
}
// print(temp.size());
// vprint(all(temp));
assert(temp.size() % 2 == 0);
for(int i = 0; i < temp.size(); i += 2) {
int x = temp[i], y = temp[i + 1];
ans.push_back({x, n - y + 1});
swap(a[x], a[y]);
swap(a[n - x + 1], a[n - y + 1]);
}
rep(i, 1, n / 2) if(a[i] != i && !vis[i]){
int cur = a[i];
temp.clear(), temp.push_back(i);
vis[i] = 1;
while(cur != i) {
temp.push_back(cur);
vis[cur] = 1;
cur = a[cur];
}
rrep(j, 0, signed(temp.size()) - 2) {
ans.push_back({temp[j], temp[j + 1]});
}
}
cout << ans.size() << " " << ans.size() << "\n";
for(auto i : ans) cout << i.first << " " << i.second << "\n";
}
};
using namespace solver;
signed main() {
ios::sync_with_stdio(false), cin.tie(0);
int t; cin >> t;
while(t--) {
int n; cin >> n;
init_(n);
rep(i, 1, n) cin >> a[i];
solve();
}
return 0;
}
Compilation message
cat.cpp:4: warning: ignoring '#pragma loop ' [-Wunknown-pragmas]
4 | #pragma loop-opt(on)
|
cat.cpp:20:13: warning: use of 'auto' in parameter declaration only available with '-fconcepts-ts'
20 | void vprint(auto L, auto R) { while(L < R)cerr << *L << " \n"[next(L) == R], ++L; }
| ^~~~
cat.cpp:20:21: warning: use of 'auto' in parameter declaration only available with '-fconcepts-ts'
20 | void vprint(auto L, auto R) { while(L < R)cerr << *L << " \n"[next(L) == R], ++L; }
| ^~~~
cat.cpp: In function 'void solver::solve()':
cat.cpp:85:20: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
85 | for(int i = 0; i < temp.size(); i += 2) {
| ~~^~~~~~~~~~~~~
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Runtime error |
1 ms |
460 KB |
Execution killed with signal 6 |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
36 ms |
932 KB |
Output is correct |
| 2 |
Correct |
28 ms |
1020 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Runtime error |
1 ms |
460 KB |
Execution killed with signal 6 |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
36 ms |
932 KB |
Output is correct |
| 2 |
Correct |
28 ms |
1020 KB |
Output is correct |
| 3 |
Correct |
658 ms |
21496 KB |
Output is correct |
| 4 |
Correct |
599 ms |
21672 KB |
Output is correct |
| 5 |
Correct |
662 ms |
27404 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Runtime error |
1 ms |
460 KB |
Execution killed with signal 6 |
