#993401 (C++14) No.2791 Beginner Contest

• 問題: No.2791 Beginner Contest
• ユーザー: ななな
• 提出日時: 2024-07-09 20:56:18
• 言語: C++14 (gcc 13.3.0 + boost 1.87.0)
• 結果: AC
• 実行時間: 12 ms / 2,000 ms
• コード長: 3,040 bytes
• コンパイル時間: 1,686 ms
• コンパイル使用メモリ: 170,668 KB
• 実行使用メモリ: 6,944 KB
• 最終ジャッジ日時: 2024-07-09 20:56:21
• 合計ジャッジ時間: 2,823 ms
• ジャッジサーバーID （参考情報）: judge4 / judge3

ファイルパターン	結果
sample	AC * 3
other	AC * 17

ソースコード

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#include "bits/stdc++.h"
using namespace std;
#define int long long
#define ld long double
#define rep(i, n) for (int i = 0; i < n; i++)
#define ll long long
#define rep(i, n) for (int i = 0; i < n; i++)
template <long long mod> struct modint {
  modint(ll v = 0) : value(normalize(v)) {}
  ll val() const { return value; }
  void normalize() { value = normalize(value); }
  ll normalize(ll v) {
    if (v <= mod && v >= -mod) {
      if (v < 0)
        v += mod;
      return v;
    }
    if (v > 0 && v < 2 * mod) {
      v -= mod;
      return v;
    }
    if (v < 0 && v > -2 * mod) {
      v += 2 * mod;
      return v;
    }
    v %= mod;
    if (v < 0)
      v += mod;
    return v;
  }
  modint<mod> &operator=(ll v) {
    value = normalize(v);
    return *this;
  }
  bool operator==(const modint &o) const { return value == o.val(); }
  bool operator!=(const modint &o) const { return value != o.val(); }
  const modint &operator+() const { return *this; }
  const modint &operator-() const { return value ? mod - value : 0; }
  const modint operator+(const modint &o) const { return value + o.val(); }
  modint &operator+=(const modint &o) {
    value += o.val();
    if (value >= mod)
      value -= mod;
    return *this;
  }
  const modint operator-(const modint &o) const { return value - o.val(); }
  modint &operator-=(const modint &o) {
    value -= o.val();
    if (value < 0)
      value += mod;
    return *this;
  }
  const modint operator*(const modint &o) const {
    return (value * o.val()) % mod;
  }
  modint &operator*=(const modint &o) {
    value *= o.val();
    value %= mod;
    return *this;
  }
  const modint operator/(const modint &o) const { return operator*(o.inv()); }
  modint &operator/=(const modint &o) { return operator*=(o.inv()); }
  const modint pow(ll n) const {
    modint ans = 1, x(value);
    while (n > 0) {
      if (n & 1)
        ans *= x;
      x *= x;
      n >>= 1;
    }
    return ans;
  }
  const modint inv() const {
    ll a = value, b = mod, u = 1, v = 0;
    while (b) {
      ll t = a / b;
      a -= t * b;
      swap(a, b);
      u -= t * v;
      swap(u, v);
    }
    return u;
  }
  friend ostream &operator<<(ostream &os, const modint &x) {
    return os << x.val();
  }
  template <typename T> friend modint operator+(T t, const modint &o) {
    return o + t;
  }
  template <typename T> friend modint operator-(T t, const modint &o) {
    return -o + t;
  }
  template <typename T> friend modint operator*(T t, const modint &o) {
    return o * t;
  }
  template <typename T> friend modint operator/(T t, const modint &o) {
    return o.inv() * t;
  }
private:
  ll value;
};
using mint = modint<998244353>;
signed main() {
  int n, k;
  cin >> n >> k;
  mint ans = 0;
  vector<mint> a(2e5 + 2);
  int cnt = 1;
  a[0] = 1;
  rep(i, 2e5 + 2) {
    if (i == 0)
      continue;
    a[i] = a[i - 1] * i;
  }
  rep(i, n + 1) {
    int t = n - k * i;
    if (t < 0)
      continue;
    ans += mint(a[(t + i)]) / mint(a[t]) / mint(a[i]);
  }
  cout << ans << endl;
}
 
 
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