cp/codeforces/826/1741d.cc
2025-11-03 13:12:18 -05:00

107 lines
1.9 KiB
C++

#include <bits/stdc++.h> // {{{
#include <version>
#ifdef __cpp_lib_ranges_enumerate
#include <ranges>
namespace rv = std::views;
namespace rs = std::ranges;
#endif
#pragma GCC optimize("O2,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
using namespace std;
using i16 = int16_t;
using u16 = uint16_t;
using i32 = int32_t;
using u32 = uint32_t;
using i64 = int64_t;
using u64 = uint64_t;
using f64 = double;
using f128 = long double;
#if __cplusplus >= 202002L
template <typename T> constexpr T MIN = std::numeric_limits<T>::min();
template <typename T> constexpr T MAX = std::numeric_limits<T>::max();
#endif
#ifdef LOCAL
#define db(...) std::print(__VA_ARGS__)
#define dbln(...) std::println(__VA_ARGS__)
#else
#define db(...)
#define dbln(...)
#endif
// }}}
void solve() {
u32 n;
cin >> n;
vector<u32> a(n);
for (auto &e : a)
cin >> e;
auto f = [&](auto &&self, i32 l, i32 r) -> i64 {
if (l + 1 == r) {
return 0;
}
i32 m = l + (r - l) / 2;
i64 left = self(self, l, m);
i64 right = self(self, m, r);
if (left == -1 || right == -1) {
return -1;
}
bool ok = true;
for (i32 i = l; i < r - 1; ++i) {
ok = ok && (a[i] < a[i + 1]);
}
if (ok) {
return left + right;
}
ok = true;
i32 j = m;
for (i32 i = 0; i < r - l - 1; ++i) {
i32 next = (j == r - 1 ? l : j + 1);
ok = ok && (a[j] < a[next]);
j = next;
}
if (ok) {
for (i32 i = 0; i < m - l; ++i) {
swap(a[l + i], a[m + i]);
}
return 1 + left + right;
}
return -1;
};
cout << f(f, 0, n) << '\n';
}
int main() { // {{{
std::cin.exceptions(std::cin.failbit);
#ifdef LOCAL
std::cerr.rdbuf(std::cout.rdbuf());
std::cout.setf(std::ios::unitbuf);
std::cerr.setf(std::ios::unitbuf);
#else
std::cin.tie(nullptr)->sync_with_stdio(false);
#endif
u32 tc = 1;
std::cin >> tc;
for (u32 t = 0; t < tc; ++t) {
solve();
}
return 0;
}
// }}}