Torni

#include <bits/stdc++.h>
#define ll long long int

using namespace std;

int M = 1e9+7;


ll k[101010];

ll f(int a)
{
	if(k[a]) return k[a];
	if(a<0) return 0;

	k[a] = (6*f(a-1))%M;
	k[a] = (k[a]-(7*f(a-2)))%M;

	return k[a];
}

int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);

	int n; cin >> n;
	k[0] = 1;
	k[1] = 2;
	k[2] = 8;

	cout << f(n) << "\n";


	return 0;
}

Test 1

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 2

Group: 2, 3

Verdict: WRONG ANSWER

Test 3

Group: 3

Verdict: WRONG ANSWER