Submission #474971

#	Time	Username	Problem	Language	Result	Execution time	Memory
474971		hhhhaura	Cat (info1cup19_cat)	C++14	25 / 100	612 ms	28512 KiB

cat

#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) { 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]) {
			if(inv[i] != top[i] && b[inv[i]]) {
				b[i] = 0, b[inv[i]] = 0;
				ans.push_back({i, n - inv[i] + 1});
				swap(a[i], a[inv[i]]);
				swap(a[n - i + 1], a[n - inv[i] + 1]);
			}
		}
		vector<int> temp;
		rep(i, 1, n / 2) if(b[i]) temp.push_back(i);
//		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];
				assert(temp.size() <= n);
			}
			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 (stderr)

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) { 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) { cerr << *L << " \n"[next(L) == R], ++L; }
      |                     ^~~~
cat.cpp: In function 'void solver::solve()':
cat.cpp:80:20: 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]
   80 |   for(int i = 0; i < temp.size(); i += 2) {
      |                  ~~^~~~~~~~~~~~~
In file included from /usr/include/c++/10/cassert:44,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:33,
                 from cat.cpp:2:
cat.cpp:94:24: warning: comparison of integer expressions of different signedness: 'std::vector<long long int>::size_type' {aka 'long unsigned int'} and 'long long int' [-Wsign-compare]
   94 |     assert(temp.size() <= n);
      |            ~~~~~~~~~~~~^~~~

• Subtask 1: 0 / 15
• Subtask 2: 10 / 10
• Subtask 3: 0 / 25
• Subtask 4: 15 / 15
• Subtask 5: 0 / 35