This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
#define int long long
#define float double
#define pb push_back
#define F first
#define S second
#define T int t; cin >> t; while(t--)
#define IOS ios::sync_with_stdio(); cin.tie(0); cout.tie(0);
using namespace std;
const int inf = 8e18;
const int N = 1e6 + 6;
const int M = 1e3 + 3;
const int mod = 1e9 + 7;
const float pi = atan(1) * 4;
int a[N];
int n, m;
map<int, int> Pos;
vector<pair<int, int>> v;
void Swap(int i, int p)
{
swap(Pos[a[i]], Pos[a[p]]);
swap(a[i], a[p]);
v.pb({i, p});
swap(Pos[a[n - p + 1]], Pos[a[n - p + 1]]);
swap(a[n - i + 1], a[n - p + 1]);
}
main()
{
T
{
v.clear();
Pos.clear();
cin >> n;
for(int i = 1; i <= n ; i++)
cin >> a[i], Pos[a[i]] = i;
for(int i = 1; i <= n / 2; i++)
{
int p = Pos[i];
if (a[i] == i)
continue;
if (p < n / 2)
Swap(i, p);
else
{
if (n - p - 1 == i)
{
Swap(i, i + 1);
Swap(i, p);
}
else
Swap(i, p);
}
}
bool ok = true;
for(int i = 1; i <= n; i++)
ok &= a[i] >= a[i - 1];
if (!ok)
{
cout << "-1\n";
continue;
}
cout << v.size() << ' ' << v.size() << '\n';
for(auto x: v)
cout << x.F << ' ' << x.S << '\n';
}
}
Compilation message (stderr)
cat.cpp:31:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
31 | main()
| ^~~~
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