#include<bits/stdc++.h>
#define pb emplace_back
#define AI(i) begin(i), end(i)
using namespace std;
using ll = long long;
#ifdef KEV
#define DE(args...) kout("[ " + string(#args) + " ] = ", args)
void kout() {cerr << endl;}
template<class T1, class ...T2>
void kout (T1 v, T2 ...e) { cerr << v << ' ', kout(e...); }
template<class T>
void debug(T L, T R) { while (L != R) cerr << *L << " \n"[next(L)==R], ++L; }
#else
#define DE(...) 0
#define debug(...) 0
#endif
const int MAX_N = 300010;
int n;
vector<pair<int,int>> op;
// just the front half
void swap_sort(vector<int> p) {
}
bool valid(vector<int> p) {
int cnt = 0, m = n / 2;
for (int l = 0, r = n-1;l < r;++l, --r) {
if ((p[l]>m) ^ (p[r]<=m))
return false;
if (p[l] > m)
++cnt;
}
if (cnt & 1)
return false;
vector<int> ln, rn;
for (int i = 0;i < m;++i)
if (p[i] > m)
ln.pb(i);
for (int i = n-1;i >= m;--i)
if (p[i] <= m)
rn.pb(i);
assert(cnt == ln.size() && cnt == rn.size());
vector<int> pos(n);
for (int i = 0;i < n;++i)
pos[ p[i] ] = i;
auto sw = [&](int x, int y) {
swap(p[x], p[y]), swap(pos[ p[x] ], pos[ p[y] ]);
};
auto do_op = [&](int x, int y) {
DE(x, y);
int a = x, b = y, c = n - x - 1, d = n - y - 1;
sw(a, b), sw(c, d);
};
for (int i = 0;i < cnt;i += 2)
do_op(ln[i], rn[i+1]);
for (int i = 0;i < m;++i) {
debug(AI(p));
while (i+1 != p[i]) {
do_op(i, pos[i+1]);
}
}
for (int i = 0;i < n;++i)
if (p[i] != i+1)
return false;
DE(__LINE__);
return true;
}
// make p good enough so that I can do swap sort on it
void pair_good(vector<int> &p) {
}
bool solve() {
cin >> n;
vector<int> p(n);
for (int &i : p)
cin >> i;
if (!valid(p))
return false;
else
return true;
pair_good(p);
swap_sort(p);
return true;
}
signed main() {
ios_base::sync_with_stdio(0), cin.tie(0);
int T;
cin >> T;
while (T--) {
op.clear();
if (!solve())
cout << -1 << '\n';
else {
cout << op.size() << ' ' << op.size() << '\n';
for (auto [a, b] : op)
cout << a+1 << ' ' << b+1 << '\n';
}
}
}
Compilation message
In file included from /usr/include/c++/9/cassert:44,
from /usr/include/x86_64-linux-gnu/c++/9/bits/stdc++.h:33,
from cat.cpp:1:
cat.cpp: In function 'bool valid(std::vector<int>)':
cat.cpp:41:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
41 | assert(cnt == ln.size() && cnt == rn.size());
| ~~~~^~~~~~~~~~~~
cat.cpp:41:33: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
41 | assert(cnt == ln.size() && cnt == rn.size());
| ~~~~^~~~~~~~~~~~
cat.cpp: In lambda function:
cat.cpp:14:17: warning: statement has no effect [-Wunused-value]
14 | #define DE(...) 0
| ^
cat.cpp:49:3: note: in expansion of macro 'DE'
49 | DE(x, y);
| ^~
cat.cpp: In function 'bool valid(std::vector<int>)':
cat.cpp:15:20: warning: statement has no effect [-Wunused-value]
15 | #define debug(...) 0
| ^
cat.cpp:57:3: note: in expansion of macro 'debug'
57 | debug(AI(p));
| ^~~~~
cat.cpp:14:17: warning: statement has no effect [-Wunused-value]
14 | #define DE(...) 0
| ^
cat.cpp:65:2: note: in expansion of macro 'DE'
65 | DE(__LINE__);
| ^~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
3 ms |
640 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
1 ms |
532 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
3 ms |
640 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
1 ms |
532 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Runtime error |
3 ms |
640 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |
