diff --git a/CSES Problem Set/Counting Towers.cpp b/CSES Problem Set/Counting Towers.cpp new file mode 100644 index 0000000..6811701 --- /dev/null +++ b/CSES Problem Set/Counting Towers.cpp @@ -0,0 +1,94 @@ +/* Problem URL: https://cses.fi/problemset/task/2413 */ + +#include + +using namespace std; + +#define V vector + +#define rmin(a, b) a = min(a, b) +#define rmax(a, b) a = max(a, b) + +#define rep(i, lim) for (size_t i = 0; i < (lim); i++) +#define nrep(i, s, lim) for (size_t i = s; i < (lim); i++) + +#define repv(i, v) for (auto &i : (v)) +#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; } +#define sortv(v) sort(v.begin(), v.end()) +#define all(v) (v).begin(), (v).end() + +using vi = vector; +using vvi = vector; +using vvvi = vector; +using vvvvi = vector; + +using ll = long long; + +using vl = vector; +using vvl = vector; +using vvvl = vector; +using vvvvl = vector; + +template +auto operator<<(ostream &os, const vector &vec)->ostream& { + os << vec[0]; + for (size_t i = 1; i < vec.size(); i++) { + os << ' ' << vec[i]; + } + os << '\n'; + return os; +} + +template +auto operator>>(istream &is, vector &vec)->istream& { + for (auto &i : vec) { + is >> i; + } + return is; +} + +template +auto operator<<(ostream &os, const vector> &vec)->ostream& { + for (auto &i : vec) { + os << i[0]; + for (size_t j = 1; j < i.size(); j++) { + os << ' ' << i[j]; + } + os << '\n'; + } + return os; +} + +template +auto operator>>(istream &is, vector> &vec)->istream& { + for (auto &i : vec) { + for (auto &j : i) { + is >> j; + } + } + return is; +} + +const ll mod = 1e9 + 7; + +int main() +{ + ios::sync_with_stdio(false); + cin.tie(nullptr); + + vvl dp(1e6 + 1, vl(2)); + dp[1][0] = 1; + dp[1][1] = 1; + for (size_t i = 2; i <= (ll)1e6; i++) { + dp[i][0] = (dp[i - 1][0] * 4 + dp[i - 1][1]) % mod; + dp[i][1] = (dp[i - 1][0] + dp[i - 1][1] * 2) % mod; + } + + int t; + cin >> t; + while (t--) { + int n; + cin >> n; + cout << (dp[n][0] + dp[n][1]) % mod << '\n'; + } +}