#944458 (C++23) No.2511 Mountain Sequence

• 問題: No.2511 Mountain Sequence
• ユーザー: Misuki
• 提出日時: 2024-01-17 02:10:02
• 言語: C++23 (gcc 12.3.0 + boost 1.83.0)
• 結果: AC
• 実行時間: 9 ms / 2,000 ms
• コード長: 4,965 bytes
• コンパイル時間: 2,527 ms
• コンパイル使用メモリ: 196,272 KB
• 実行使用メモリ: 6,944 KB
• 最終ジャッジ日時: 2024-09-28 03:08:18
• 合計ジャッジ時間: 4,233 ms
• ジャッジサーバーID （参考情報）: judge2 / judge1

入力	結果	実行時間; 実行使用メモリ
testcase_00	AC	7 ms; 6,816 KB
testcase_01	AC	7 ms; 6,940 KB
testcase_02	AC	8 ms; 6,940 KB
testcase_03	AC	7 ms; 6,944 KB
testcase_04	AC	7 ms; 6,944 KB
testcase_05	AC	8 ms; 6,940 KB
testcase_06	AC	7 ms; 6,940 KB
testcase_07	AC	8 ms; 6,940 KB
testcase_08	AC	7 ms; 6,940 KB
testcase_09	AC	7 ms; 6,944 KB
testcase_10	AC	8 ms; 6,944 KB
testcase_11	AC	8 ms; 6,944 KB
testcase_12	AC	7 ms; 6,944 KB
testcase_13	AC	8 ms; 6,940 KB
testcase_14	AC	8 ms; 6,940 KB
testcase_15	AC	8 ms; 6,940 KB
testcase_16	AC	7 ms; 6,944 KB
testcase_17	AC	8 ms; 6,944 KB
testcase_18	AC	8 ms; 6,940 KB
testcase_19	AC	8 ms; 6,940 KB
testcase_20	AC	8 ms; 6,940 KB
testcase_21	AC	8 ms; 6,944 KB
testcase_22	AC	8 ms; 6,940 KB
testcase_23	AC	7 ms; 6,940 KB
testcase_24	AC	7 ms; 6,944 KB
testcase_25	AC	8 ms; 6,944 KB
testcase_26	AC	7 ms; 6,944 KB
testcase_27	AC	8 ms; 6,940 KB
testcase_28	AC	7 ms; 6,944 KB
testcase_29	AC	8 ms; 6,940 KB
testcase_30	AC	7 ms; 6,944 KB
testcase_31	AC	9 ms; 6,940 KB
testcase_32	AC	7 ms; 6,944 KB
testcase_33	AC	8 ms; 6,940 KB
testcase_34	AC	8 ms; 6,944 KB

ソースコード

#pragma GCC optimize("O2")
#include <algorithm>
#include <array>
#include <bit>
#include <bitset>
#include <cassert>
#include <cctype>
#include <cfenv>
#include <cfloat>
#include <chrono>
#include <cinttypes>
#include <climits>
#include <cmath>
#include <compare>
#include <complex>
#include <concepts>
#include <cstdarg>
#include <cstddef>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <deque>
#include <fstream>
#include <functional>
#include <initializer_list>
#include <iomanip>
#include <ios>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <map>
#include <memory>
#include <new>
#include <numbers>
#include <numeric>
#include <ostream>
#include <queue>
#include <random>
#include <ranges>
#include <set>
#include <span>
#include <sstream>
#include <stack>
#include <streambuf>
#include <string>
#include <tuple>
#include <type_traits>
#include <variant>

//#define int ll
#define INT128_MAX (__int128)(((unsigned __int128) 1 << ((sizeof(__int128) * __CHAR_BIT__) - 1)) - 1)
#define INT128_MIN (-INT128_MAX - 1)

#ifdef DEBUG
#define dbg(x) cout << (#x) << " = " << x << '\n'
#else
#define dbg(x)
#endif

namespace R = std::ranges;
namespace V = std::views;

using namespace std;

using ll = long long;
using ull = unsigned long long;
using ldb = long double;
//#define double ldb

template<class T, size_t N>
ostream& operator<<(ostream& os, const array<T, N> &arr) {
  for(const T &X : arr)
    os << X << ' ';
  return os;
}
template<class T>
ostream& operator<<(ostream& os, const vector<T> &vec) {
  for(const T &X : vec)
    os << X << ' ';
  return os;
}
template<class T>
ostream& operator<<(ostream& os, const set<T> &s) {
  for(const T &x : s)
    os << x << ' ';
  return os;
}

/**
 * template name: MontgomeryModInt
 * author: Misuki
 * reference: https://github.com/NyaanNyaan/library/blob/master/modint/montgomery-modint.hpp#L10
 * last update: 2023/11/30
 * note: mod should be a prime less than 2^30.
 */

template<uint32_t mod>
struct MontgomeryModInt {
  using mint = MontgomeryModInt;
  using i32 = int32_t;
  using u32 = uint32_t;
  using u64 = uint64_t;

  static constexpr u32 get_r() {
    u32 res = 1, base = mod;
    for(i32 i = 0; i < 31; i++)
      res *= base, base *= base;
    return -res;
  }

  static constexpr u32 get_mod() {
    return mod;
  }

  static constexpr u32 n2 = -u64(mod) % mod; //2^64 % mod
  static constexpr u32 r = get_r(); //-P^{-1} % 2^32

  u32 a;

  static u32 reduce(const u64 &b) {
    return (b + u64(u32(b) * r) * mod) >> 32;
  }

  static u32 transform(const u64 &b) {
    return reduce(u64(b) * n2);
  }

  MontgomeryModInt() : a(0) {}
  MontgomeryModInt(const int64_t &b) 
    : a(transform(b % mod + mod)) {}

  mint pow(u64 k) const {
    mint res(1), base(*this);
    while(k) {
      if (k & 1) 
        res *= base;
      base *= base, k >>= 1;
    }
    return res;
  }

  mint inverse() const { return (*this).pow(mod - 2); }

  u32 get() const {
    u32 res = reduce(a);
    return res >= mod ? res - mod : res;
  }

  mint& operator+=(const mint &b) {
    if (i32(a += b.a - 2 * mod) < 0) a += 2 * mod;
    return *this;
  }

  mint& operator-=(const mint &b) {
    if (i32(a -= b.a) < 0) a += 2 * mod;
    return *this;
  }

  mint& operator*=(const mint &b) {
    a = reduce(u64(a) * b.a);
    return *this;
  }

  mint& operator/=(const mint &b) {
    a = reduce(u64(a) * b.inverse().a);
    return *this;
  }

  mint operator-() { return mint() - mint(*this); }
  bool operator==(mint b) const {
    return (a >= mod ? a - mod : a) == (b.a >= mod ? b.a - mod : b.a);
  }
  bool operator!=(mint b) const {
    return (a >= mod ? a - mod : a) != (b.a >= mod ? b.a - mod : b.a);
  }

  friend mint operator+(mint a, mint b) { return a += b; }
  friend mint operator-(mint a, mint b) { return a -= b; }
  friend mint operator*(mint a, mint b) { return a *= b; }
  friend mint operator/(mint a, mint b) { return a /= b; }

  friend ostream& operator<<(ostream& os, const mint& b) {
    return os << b.get();
  }
  friend istream& operator>>(istream& is, mint& b) {
    int64_t val;
    is >> val;
    b = mint(val);
    return is;
  }
};

using mint = MontgomeryModInt<998244353>;

/**
 * template name: comb
 * author: Misuki
 * last update: 2023/01/22
 * note: remember to call init() before using it.
 */

const int MAX = 400000;
mint fac[MAX], facInv[MAX];
void init() {
  fac[0] = 1;
  for(int i = 1; i < MAX; i++)
    fac[i] = fac[i - 1] * i;
  facInv[MAX - 1] = 1 / fac[MAX - 1];
  for(int i = MAX - 2; i >= 0; i--)
    facInv[i] = facInv[i + 1] * (i + 1);
}

mint C(int a, int b) {
  if (b < 0 or a < b)
    return 0;
  else
    return fac[a] * facInv[b] * facInv[a - b];
}

signed main() {
  ios::sync_with_stdio(false), cin.tie(NULL);

  init();

  int n, m; cin >> n >> m;

  mint ans = 0;
  for(int j = 0; j < m; j++)
    ans += C(2 * j, n - 1);

  cout << ans << '\n';

  return 0;
}