Torni

#include <iostream>
using namespace std;
const int Z = 1e9+7;
const int MN = 1<<20;
long long A[MN], B[MN];
int main() {
	A[0]=B[0]=1;
	for(int i=1; i<MN; ++i) {
		A[i] = (4*A[i-1] + B[i-1])%Z;
		B[i] = (A[i-1] + 2*B[i-1])%Z;
	}
	int t;cin>>t;
	while(t--){
		int n;cin>>n;
		cout<<(A[n-1]+B[n-1])%Z<<'\n';
	}
}

Test 1

Group: 1, 2, 3

Verdict: ACCEPTED

Test 2

Group: 2, 3

Verdict: ACCEPTED

Test 3

Group: 3

Verdict: ACCEPTED