Dynamic Mod Int (math/dynamic_mod_int.hpp)

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• Last update: 2025-11-15 20:52:05+09:00
• Include: #include "math/dynamic_mod_int.hpp"

Depends on

• template/constant.hpp
• template/include.hpp
• template/macro.hpp
• 提出用テンプレート (template/template.hpp)
• template/type_alias.hpp
• Choose Minimum / Maximum (utility/choose_min_max.hpp)
• utility/set_io.hpp

Required by

• test/utility/next_combination.test.cpp

Verified with

• test/math/binomial.test.cpp

Code

#pragma once

#include "../template/template.hpp"

/**
 * @brief Dynamic Mod Int
 * @note 仮実装
 */
class DynamicModInt {
  private:
    int v;
    static int m;

  public:
    DynamicModInt() : v(0) {}
    DynamicModInt(ll _v) : v(int(((_v % m) + m) % m)) {}

    static void set_mod(int _m) {
        m = _m;
        assert(m <= INT_MAX / 2);

        return;
    }

    static DynamicModInt raw(int _v) {
        DynamicModInt res;
        res.v = _v;

        return res;
    }

    static int mod() { return m; }
    int val() const { return v; }

    friend bool operator==(const DynamicModInt& lhs, const DynamicModInt& rhs) {
        return lhs.v == rhs.v;
    }

    friend bool operator!=(const DynamicModInt& lhs, const DynamicModInt& rhs) {
        return !(lhs == rhs);
    }

    DynamicModInt& operator+=(const DynamicModInt& rhs) {
        v += rhs.v;
        if (m <= v) {
            v -= m;
        }

        return *this;
    }

    DynamicModInt& operator-=(const DynamicModInt& rhs) {
        if (v < rhs.v) {
            v += m;
        }
        v -= rhs.v;

        return *this;
    }

    DynamicModInt& operator*=(const DynamicModInt& rhs) {
        v = (ull(v) * rhs.val()) % m;

        return *this;
    }

    DynamicModInt& operator/=(const DynamicModInt& rhs) {
        assert(rhs.v != 0);

        return *this *= rhs.inv();
    }

    friend DynamicModInt operator+(const DynamicModInt& lhs, const DynamicModInt& rhs) {
        return DynamicModInt(lhs) += rhs;
    }

    friend DynamicModInt operator-(const DynamicModInt& lhs, const DynamicModInt& rhs) {
        return DynamicModInt(lhs) -= rhs;
    }

    friend DynamicModInt operator*(const DynamicModInt& lhs, const DynamicModInt& rhs) {
        return DynamicModInt(lhs) *= rhs;
    }

    friend DynamicModInt operator/(const DynamicModInt& lhs, const DynamicModInt& rhs) {
        return DynamicModInt(lhs) /= rhs;
    }

    DynamicModInt pow(ll y) const {
        DynamicModInt res = raw(1);
        DynamicModInt x = *this;

        while (0 < y) {
            if (y & 1) {
                res *= x;
            }

            x *= x;
            y >>= 1;
        }

        return res;
    }

    DynamicModInt inv() const { return pow(m - 2); }
};

int DynamicModInt::m = 998244353;

#line 2 "math/dynamic_mod_int.hpp"

#line 2 "template/template.hpp"

/**
 * @author ku_senjan
 * @title 提出用テンプレート
 * @see https://github.com/kogetsu0728/ku-library
 */

#line 2 "template/constant.hpp"

#line 2 "template/include.hpp"

#ifdef LOCAL
#define _GLIBCXX_DEBUG
#endif

#include <bits/stdc++.h>
using namespace std;
#line 2 "template/type_alias.hpp"

#line 4 "template/type_alias.hpp"

using uint = unsigned int;
using ll = long long;
using ull = unsigned long long;

using ld = long double;

template <class T, bool REVERSE = false>
using heap = priority_queue<T, vector<T>, conditional_t<REVERSE, greater<T>, less<T>>>;
#line 5 "template/constant.hpp"

template <class T>
inline constexpr T INF = numeric_limits<T>::max() / 2;

inline constexpr array<int, 4> DY4 = {0, -1, 0, 1};
inline constexpr array<int, 4> DX4 = {1, 0, -1, 0};
inline constexpr array<int, 8> DY8 = {0, -1, -1, -1, 0, 1, 1, 1};
inline constexpr array<int, 8> DX8 = {1, 1, 0, -1, -1, -1, 0, 1};

inline constexpr char LF = '\n';
#line 2 "template/macro.hpp"

#line 5 "template/macro.hpp"

/**
 * @see https://trap.jp/post/1224/
 */

#ifdef LOCAL
inline constexpr bool IS_LOCAL = true;
#else
inline constexpr bool IS_LOCAL = false;
#endif

#define IF_LOCAL if constexpr (IS_LOCAL)

#define all(a) begin(a), end(a)
#define rall(a) rbegin(a), rend(a)

#define overload4(a, b, c, d, e, ...) e

#define rep1(i, a) for (ll i = 0; (i) < (ll)(a); ++(i))
#define rep2(i, a, b) for (ll i = (ll)(a); (i) < (ll)(b); ++(i))
#define rep3(i, a, b, c) for (ll i = (ll)(a); (i) < (ll)(b); (i) += (ll)(c))
#define rep(...) overload4(__VA_ARGS__, rep3, rep2, rep1)(__VA_ARGS__)

#define rrep1(i, a) for (ll i = (ll)(a); (i) >= 0; --(i))
#define rrep2(i, a, b) for (ll i = (ll)(a); (i) >= (ll)(b); --(i))
#define rrep3(i, a, b, c) for (ll i = (ll)(a); (i) >= (ll)(b); (i) -= (ll)(c))
#define rrep(...) overload4(__VA_ARGS__, rrep3, rrep2, rrep1)(__VA_ARGS__)
#line 13 "template/template.hpp"

#line 2 "utility/choose_min_max.hpp"

/**
 * @title Choose Minimum / Maximum
 */

template <class T>
bool chmin(T& a, const T& b) {
    if (a > b) {
        a = b;
        return true;
    }

    return false;
}

template <class T>
bool chmax(T& a, const T& b) {
    if (a < b) {
        a = b;
        return true;
    }

    return false;
}
#line 2 "utility/set_io.hpp"

#line 4 "utility/set_io.hpp"

void set_io(int d = 16) {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(d);

    return;
}
#line 4 "math/dynamic_mod_int.hpp"

/**
 * @brief Dynamic Mod Int
 * @note 仮実装
 */
class DynamicModInt {
  private:
    int v;
    static int m;

  public:
    DynamicModInt() : v(0) {}
    DynamicModInt(ll _v) : v(int(((_v % m) + m) % m)) {}

    static void set_mod(int _m) {
        m = _m;
        assert(m <= INT_MAX / 2);

        return;
    }

    static DynamicModInt raw(int _v) {
        DynamicModInt res;
        res.v = _v;

        return res;
    }

    static int mod() { return m; }
    int val() const { return v; }

    friend bool operator==(const DynamicModInt& lhs, const DynamicModInt& rhs) {
        return lhs.v == rhs.v;
    }

    friend bool operator!=(const DynamicModInt& lhs, const DynamicModInt& rhs) {
        return !(lhs == rhs);
    }

    DynamicModInt& operator+=(const DynamicModInt& rhs) {
        v += rhs.v;
        if (m <= v) {
            v -= m;
        }

        return *this;
    }

    DynamicModInt& operator-=(const DynamicModInt& rhs) {
        if (v < rhs.v) {
            v += m;
        }
        v -= rhs.v;

        return *this;
    }

    DynamicModInt& operator*=(const DynamicModInt& rhs) {
        v = (ull(v) * rhs.val()) % m;

        return *this;
    }

    DynamicModInt& operator/=(const DynamicModInt& rhs) {
        assert(rhs.v != 0);

        return *this *= rhs.inv();
    }

    friend DynamicModInt operator+(const DynamicModInt& lhs, const DynamicModInt& rhs) {
        return DynamicModInt(lhs) += rhs;
    }

    friend DynamicModInt operator-(const DynamicModInt& lhs, const DynamicModInt& rhs) {
        return DynamicModInt(lhs) -= rhs;
    }

    friend DynamicModInt operator*(const DynamicModInt& lhs, const DynamicModInt& rhs) {
        return DynamicModInt(lhs) *= rhs;
    }

    friend DynamicModInt operator/(const DynamicModInt& lhs, const DynamicModInt& rhs) {
        return DynamicModInt(lhs) /= rhs;
    }

    DynamicModInt pow(ll y) const {
        DynamicModInt res = raw(1);
        DynamicModInt x = *this;

        while (0 < y) {
            if (y & 1) {
                res *= x;
            }

            x *= x;
            y >>= 1;
        }

        return res;
    }

    DynamicModInt inv() const { return pow(m - 2); }
};

int DynamicModInt::m = 998244353;

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