문제
풀이
#include <iostream>
#include <vector>
#define MOD 1000000007
using namespace std;
void solve(void) {
int n; cin >> n;
vector<long long> dp1(n+1, 1), dp2(n+1, 0);
for (int i=1; i<=n; i++) {
dp1[i] = (24 * dp1[i-1] + 2 * dp2[i-1]) % MOD;
dp2[i] = (24 * dp2[i-1] + 2 * dp1[i-1]) % MOD;
}
cout << dp1[n];
}
int main(void) {
ios::sync_with_stdio(false);
cin.tie(nullptr);
solve();
return 0;
}