Submission #1216711

#	Time	Username	Problem	Language	Result	Execution time	Memory
1216711		Nika533	Cat (info1cup19_cat)	C++20	51.25 / 100	328 ms	16544 KiB

cat

#pragma GCC diagnostic warning "-std=c++11"
#include <bits/stdc++.h>
#define pb push_back
#define f first
#define s second
#define MOD 1000000007
#define flush fflush(stdout)
#define all(x) (x).begin(),(x).end()
#define allr(x) (x).rbegin(), (x).rend()
#define pii pair<int,int>
using namespace std;
const int N=2e5+5;
int n,m,T,k;
int arr[N],ind[N];
void q(int a, int b) {
	swap(arr[a],arr[b]); swap(arr[n-a+1],arr[n-b+1]);
}
void test_case() {
	scanf("%d",&n);
	vector<pii> op;
	for (int i=1; i<=n; i++) {
		scanf("%d",&arr[i]);
	}
	vector<int> v;
	int bestans=0;
	for (int i=1; i<=n; i++) {
		if (arr[i]+arr[n-i+1]!=n+1) {
			printf("-1\n");
			return;
		}
		if (i<=n/2) {
			if (arr[i]>arr[n-i+1]) v.pb(i);
			if (arr[i]!=i && arr[n-i+1]!=i) bestans++;
		}
	}
	int sz=v.size();
	if (sz%2) {
		printf("-1\n");
		return;
	}
	for (int i=0; i<sz; i+=2) {
		q(v[i],n-v[i+1]+1);
		op.pb({v[i],n-v[i+1]+1});
	}
	
	for (int i=1; i<=n; i++) {
		ind[arr[i]]=i;
	}
	for (int i=1; i<=n/2; i++) {
		if (arr[i]==i) continue;
		int idx=ind[i],val=arr[i];
		op.pb({i,idx});
		swap(arr[i],arr[idx]);
		swap(ind[i],ind[val]);
	}
	int SZ=op.size();
	printf("%d %d\n",bestans,SZ);
	for (auto AA:op) {
		printf("%d %d\n",AA.f,AA.s);
	}
}
main () {
	ios :: sync_with_stdio(0);
	cin.tie(0); cout.tie(0);
	T=1; scanf("%d",&T);
	while (T--) test_case();
}

Compilation message (stderr)

cat.cpp:1:32: warning: '-std=c++11' is not an option that controls warnings [-Wpragmas]
    1 | #pragma GCC diagnostic warning "-std=c++11"
      |                                ^~~~~~~~~~~~
cat.cpp:62:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   62 | main () {
      | ^~~~
cat.cpp: In function 'void test_case()':
cat.cpp:19:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   19 |         scanf("%d",&n);
      |         ~~~~~^~~~~~~~~
cat.cpp:22:22: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   22 |                 scanf("%d",&arr[i]);
      |                 ~~~~~^~~~~~~~~~~~~~
cat.cpp: In function 'int main()':
cat.cpp:65:19: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   65 |         T=1; scanf("%d",&T);
      |              ~~~~~^~~~~~~~~

• Subtask 1: 5.25 / 15
• Subtask 2: 10 / 10
• Subtask 3: 8.75 / 25
• Subtask 4: 15 / 15
• Subtask 5: 12.25 / 35