結果
問題 | No.533 Mysterious Stairs |
ユーザー |
|
提出日時 | 2020-05-29 19:21:10 |
言語 | C++17 (gcc 13.3.0 + boost 1.87.0) |
結果 |
AC
|
実行時間 | 43 ms / 5,000 ms |
コード長 | 2,455 bytes |
コンパイル時間 | 674 ms |
コンパイル使用メモリ | 75,728 KB |
最終ジャッジ日時 | 2025-01-10 16:16:54 |
ジャッジサーバーID (参考情報) |
judge3 / judge4 |
(要ログイン)
ファイルパターン | 結果 |
---|---|
other | AC * 28 |
ソースコード
#include <iostream>#include <vector>template <class T>std::vector<T> vec(int len, T elem) { return std::vector<T>(len, elem); }template <int MOD>struct ModInt {using lint = long long;int val;// constructorModInt(lint v = 0) : val(v % MOD) {if (val < 0) val += MOD;};// unary operatorModInt operator+() const { return ModInt(val); }ModInt operator-() const { return ModInt(MOD - val); }ModInt inv() const { return this->pow(MOD - 2); }// arithmeticModInt operator+(const ModInt& x) const { return ModInt(*this) += x; }ModInt operator-(const ModInt& x) const { return ModInt(*this) -= x; }ModInt operator*(const ModInt& x) const { return ModInt(*this) *= x; }ModInt operator/(const ModInt& x) const { return ModInt(*this) /= x; }ModInt pow(lint n) const {auto x = ModInt(1);auto b = *this;while (n > 0) {if (n & 1) x *= b;n >>= 1;b *= b;}return x;}// compound assignmentModInt& operator+=(const ModInt& x) {if ((val += x.val) >= MOD) val -= MOD;return *this;}ModInt& operator-=(const ModInt& x) {if ((val -= x.val) < 0) val += MOD;return *this;}ModInt& operator*=(const ModInt& x) {val = lint(val) * x.val % MOD;return *this;}ModInt& operator/=(const ModInt& x) { return *this *= x.inv(); }// comparebool operator==(const ModInt& b) const { return val == b.val; }bool operator!=(const ModInt& b) const { return val != b.val; }// I/Ofriend std::istream& operator>>(std::istream& is, ModInt& x) noexcept { return is >> x.val; }friend std::ostream& operator<<(std::ostream& os, const ModInt& x) noexcept { return os << x.val; }};constexpr int MOD = 1e9 + 7;using mint = ModInt<MOD>;void solve() {int n;std::cin >> n;auto dp = vec(4, vec(n + 1, mint(0)));dp[0][0] = 1;for (int x = 0; x < n; ++x) {for (int pd = 0; pd <= 3; ++pd) {for (int d = 1; d <= 3; ++d) {if (pd == d || x + d > n) continue;dp[d][x + d] += dp[pd][x];}}}mint ans = 0;for (int d = 0; d <= 3; ++d) ans += dp[d][n];std::cout << ans << "\n";}int main() {std::cin.tie(nullptr);std::ios::sync_with_stdio(false);solve();return 0;}