DynamicModint
(src/template/dynamic_modint.hpp)

• View this file on GitHub
• Last update: 2024-11-09 01:34:39+09:00
• Include: #include "src/template/dynamic_modint.hpp"

DynamicModint

自動で $\mathrm{mod}$ をとる構造体です．

基本的には StaticModint と同じなので違いだけを書きます．

StaticModint は $\mathrm{mod}$ がコンパイル時定数である必要がありましたが， DynamicModint はそうでない場合でも使用できます．

set_mod

void modint::set_mod(int m)

$\mathrm{mod}$ を $m$ に設定します．
最初に呼んでください．

制約

• $1 \leq m \leq 2 \times 10^9 + 1000$

計算量

• $O(1)$

Tips (複数mod)

複数種類 $\mathrm{mod}$ を使用したい場合，以下のようにできます．

using mint0 = DynamicModint<0>;
using mint1 = DynamicModint<1>;
int main(void){
    int p0, p1;
    cin >> p0 >> p1;
    mint0::set_mod(p0);
    mint1::set_mod(p1);
}

modint は DynamicModint<-1> のエイリアスになっています．

Depends on

• template (src/template/template.hpp)

Required by

• debug (src/template/debug.hpp)

Verified with

• verify/library_checker/enumerative_combinatrics/binomial_coefficient_prime_mod.test.cpp
• verify/unit_test/math/lucas.test.cpp
• verify/unit_test/template/debug.test.cpp

Code

#pragma once
#include "./template.hpp"
struct Barrett {
    explicit Barrett(const unsigned int m)
        : _m(m), im((unsigned long long)(-1) / m + 1) {}
    inline unsigned int umod() const {
        return _m;
    }
    inline unsigned int mul(const unsigned int a, const unsigned int b) const {
        unsigned long long z = a;
        z *= b;
        const unsigned long long x = (unsigned long long)(((unsigned __int128)(z)*im) >> 64);
        unsigned int v = (unsigned int)(z - x * _m);
        if(_m <= v) v += _m;
        return v;
    }

   private:
    unsigned int _m;
    unsigned long long im;
};
template <int id>
struct DynamicModint {
    using mint = DynamicModint;
    static int mod() {
        return (int)bt.umod();
    }
    static void set_mod(const int m) {
        assert(1 <= m);
        bt = Barrett(m);
    }
    static mint raw(const int v) {
        mint a;
        a._v = v;
        return a;
    }
    DynamicModint()
        : _v(0) {}
    template <class T>
    DynamicModint(const T& v) {
        static_assert(is_integral_v<T>);
        if(is_signed_v<T>) {
            long long x = (long long)(v % (long long)(umod()));
            if(x < 0) x += umod();
            _v = (unsigned int)(x);
        } else _v = (unsigned int)(v % umod());
    }
    unsigned int val() const {
        return _v;
    }
    mint& operator++() {
        ++_v;
        if(_v == umod()) _v = 0;
        return *this;
    }
    mint& operator--() {
        if(_v == 0) _v = umod();
        --_v;
        return *this;
    }
    mint operator++(int) {
        mint res = *this;
        ++*this;
        return res;
    }
    mint operator--(int) {
        mint res = *this;
        --*this;
        return res;
    }
    mint& operator+=(const mint& rhs) {
        _v += rhs._v;
        if(_v >= umod()) _v -= umod();
        return *this;
    }
    mint& operator-=(const mint& rhs) {
        _v += mod() - rhs._v;
        if(_v >= umod()) _v -= umod();
        return *this;
    }
    mint& operator*=(const mint& rhs) {
        _v = bt.mul(_v, rhs._v);
        return *this;
    }
    mint& operator/=(const mint& rhs) {
        return *this *= rhs.inv();
    }
    mint operator+() const {
        return *this;
    }
    mint operator-() const {
        return mint() - *this;
    }
    mint pow(long long n) const {
        assert(0 <= n);
        if(n == 0) return 1;
        mint x = *this, r = 1;
        while(1) {
            if(n & 1) r *= x;
            n >>= 1;
            if(n == 0) return r;
            x *= x;
        }
    }
    mint inv() const {
        const auto eg = inv_gcd(_v, mod());
        assert(eg.first == 1);
        return eg.second;
    }
    friend mint operator+(const mint& lhs, const mint& rhs) {
        return mint(lhs) += rhs;
    }
    friend mint operator-(const mint& lhs, const mint& rhs) {
        return mint(lhs) -= rhs;
    }
    friend mint operator*(const mint& lhs, const mint& rhs) {
        return mint(lhs) *= rhs;
    }
    friend mint operator/(const mint& lhs, const mint& rhs) {
        return mint(lhs) /= rhs;
    }
    friend bool operator==(const mint& lhs, const mint& rhs) {
        return lhs._v == rhs._v;
    }
    friend bool operator!=(const mint& lhs, const mint& rhs) {
        return lhs._v != rhs._v;
    }
    friend istream& operator>>(istream& in, mint& x) {
        long long a;
        in >> a;
        x = a;
        return in;
    }
    friend ostream& operator<<(ostream& out, const mint& x) {
        return out << x.val();
    }

   private:
    unsigned int _v = 0;
    static Barrett bt;
    inline static unsigned int umod() {
        return bt.umod();
    }
    inline static pair<long long, long long> inv_gcd(const long long a, const long long b) {
        if(a == 0) return {b, 0};
        long long s = b, t = a, m0 = 0, m1 = 1;
        while(t) {
            const long long u = s / t;
            s -= t * u;
            m0 -= m1 * u;
            swap(s, t);
            swap(m0, m1);
        }
        if(m0 < 0) m0 += b / s;
        return {s, m0};
    }
};
template <int id>
Barrett DynamicModint<id>::bt(998244353);
using modint = DynamicModint<-1>;

#line 2 "src/template/template.hpp"
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<long long, long long>;
#define rep(i, a, b) for(long long i = (a); i < (b); ++i)
#define rrep(i, a, b) for(long long i = (a); i >= (b); --i)
constexpr long long inf = 4e18;
struct SetupIO {
    SetupIO() {
        ios::sync_with_stdio(0);
        cin.tie(0);
        cout << fixed << setprecision(30);
    }
} setup_io;
#line 3 "src/template/dynamic_modint.hpp"
struct Barrett {
    explicit Barrett(const unsigned int m)
        : _m(m), im((unsigned long long)(-1) / m + 1) {}
    inline unsigned int umod() const {
        return _m;
    }
    inline unsigned int mul(const unsigned int a, const unsigned int b) const {
        unsigned long long z = a;
        z *= b;
        const unsigned long long x = (unsigned long long)(((unsigned __int128)(z)*im) >> 64);
        unsigned int v = (unsigned int)(z - x * _m);
        if(_m <= v) v += _m;
        return v;
    }

   private:
    unsigned int _m;
    unsigned long long im;
};
template <int id>
struct DynamicModint {
    using mint = DynamicModint;
    static int mod() {
        return (int)bt.umod();
    }
    static void set_mod(const int m) {
        assert(1 <= m);
        bt = Barrett(m);
    }
    static mint raw(const int v) {
        mint a;
        a._v = v;
        return a;
    }
    DynamicModint()
        : _v(0) {}
    template <class T>
    DynamicModint(const T& v) {
        static_assert(is_integral_v<T>);
        if(is_signed_v<T>) {
            long long x = (long long)(v % (long long)(umod()));
            if(x < 0) x += umod();
            _v = (unsigned int)(x);
        } else _v = (unsigned int)(v % umod());
    }
    unsigned int val() const {
        return _v;
    }
    mint& operator++() {
        ++_v;
        if(_v == umod()) _v = 0;
        return *this;
    }
    mint& operator--() {
        if(_v == 0) _v = umod();
        --_v;
        return *this;
    }
    mint operator++(int) {
        mint res = *this;
        ++*this;
        return res;
    }
    mint operator--(int) {
        mint res = *this;
        --*this;
        return res;
    }
    mint& operator+=(const mint& rhs) {
        _v += rhs._v;
        if(_v >= umod()) _v -= umod();
        return *this;
    }
    mint& operator-=(const mint& rhs) {
        _v += mod() - rhs._v;
        if(_v >= umod()) _v -= umod();
        return *this;
    }
    mint& operator*=(const mint& rhs) {
        _v = bt.mul(_v, rhs._v);
        return *this;
    }
    mint& operator/=(const mint& rhs) {
        return *this *= rhs.inv();
    }
    mint operator+() const {
        return *this;
    }
    mint operator-() const {
        return mint() - *this;
    }
    mint pow(long long n) const {
        assert(0 <= n);
        if(n == 0) return 1;
        mint x = *this, r = 1;
        while(1) {
            if(n & 1) r *= x;
            n >>= 1;
            if(n == 0) return r;
            x *= x;
        }
    }
    mint inv() const {
        const auto eg = inv_gcd(_v, mod());
        assert(eg.first == 1);
        return eg.second;
    }
    friend mint operator+(const mint& lhs, const mint& rhs) {
        return mint(lhs) += rhs;
    }
    friend mint operator-(const mint& lhs, const mint& rhs) {
        return mint(lhs) -= rhs;
    }
    friend mint operator*(const mint& lhs, const mint& rhs) {
        return mint(lhs) *= rhs;
    }
    friend mint operator/(const mint& lhs, const mint& rhs) {
        return mint(lhs) /= rhs;
    }
    friend bool operator==(const mint& lhs, const mint& rhs) {
        return lhs._v == rhs._v;
    }
    friend bool operator!=(const mint& lhs, const mint& rhs) {
        return lhs._v != rhs._v;
    }
    friend istream& operator>>(istream& in, mint& x) {
        long long a;
        in >> a;
        x = a;
        return in;
    }
    friend ostream& operator<<(ostream& out, const mint& x) {
        return out << x.val();
    }

   private:
    unsigned int _v = 0;
    static Barrett bt;
    inline static unsigned int umod() {
        return bt.umod();
    }
    inline static pair<long long, long long> inv_gcd(const long long a, const long long b) {
        if(a == 0) return {b, 0};
        long long s = b, t = a, m0 = 0, m1 = 1;
        while(t) {
            const long long u = s / t;
            s -= t * u;
            m0 -= m1 * u;
            swap(s, t);
            swap(m0, m1);
        }
        if(m0 < 0) m0 += b / s;
        return {s, m0};
    }
};
template <int id>
Barrett DynamicModint<id>::bt(998244353);
using modint = DynamicModint<-1>;

Back to top page