Modint
(src/modint/modint.hpp)

• View this file on GitHub
• Last update: 2024-02-23 02:15:41+09:00
• Include: #include "src/modint/modint.hpp"

• 参考実装：AC Library (初期実装)

• タイプ速度重視の簡易 modint
• 速度が欲しいとき：32 bit で加減算をちゃんと書いた Modint
• mod が素数でないとき：inv を extgcd にする
• mod が実行時に決まり，これを高速化したいとき：Barrett Reduction

Verified with

• test/FPS/FFT.test.cpp
• test/modint/modint.test.cpp

Code

const ll mod = 998244353;
struct mm {
   ll x;
   mm(ll x_ = 0) : x(x_ % mod) {
      if(x < 0) x += mod;
   }
   friend mm operator+(mm a, mm b) { return a.x + b.x; }
   friend mm operator-(mm a, mm b) { return a.x - b.x; }
   friend mm operator*(mm a, mm b) { return a.x * b.x; }
   friend mm operator/(mm a, mm b) { return a * b.inv(); }
   // 4 行コピペ  Alt + Shift + クリックで複数カーソル
   friend mm& operator+=(mm& a, mm b) { return a = a.x + b.x; }
   friend mm& operator-=(mm& a, mm b) { return a = a.x - b.x; }
   friend mm& operator*=(mm& a, mm b) { return a = a.x * b.x; }
   friend mm& operator/=(mm& a, mm b) { return a = a * b.inv(); }
   mm inv() const { return pow(mod - 2); }
   mm pow(ll b) const {
      mm a = *this, c = 1;
      while(b) {
         if(b & 1) c *= a;
         a *= a;
         b >>= 1;
      }
      return c;
   }
};

#line 1 "src/modint/modint.hpp"
const ll mod = 998244353;
struct mm {
   ll x;
   mm(ll x_ = 0) : x(x_ % mod) {
      if(x < 0) x += mod;
   }
   friend mm operator+(mm a, mm b) { return a.x + b.x; }
   friend mm operator-(mm a, mm b) { return a.x - b.x; }
   friend mm operator*(mm a, mm b) { return a.x * b.x; }
   friend mm operator/(mm a, mm b) { return a * b.inv(); }
   // 4 行コピペ  Alt + Shift + クリックで複数カーソル
   friend mm& operator+=(mm& a, mm b) { return a = a.x + b.x; }
   friend mm& operator-=(mm& a, mm b) { return a = a.x - b.x; }
   friend mm& operator*=(mm& a, mm b) { return a = a.x * b.x; }
   friend mm& operator/=(mm& a, mm b) { return a = a * b.inv(); }
   mm inv() const { return pow(mod - 2); }
   mm pow(ll b) const {
      mm a = *this, c = 1;
      while(b) {
         if(b & 1) c *= a;
         a *= a;
         b >>= 1;
      }
      return c;
   }
};

Back to top page