add: dynamic mod int

math/dynamic_mod_int.hpp

@@ -0,0 +1,112 @@
+#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;

test/math/binomial.test.cpp

@@ -1,17 +1,15 @@
 #define PROBLEM "https://judge.yosupo.jp/problem/binomial_coefficient_prime_mod"
 
 #include "../../math/binomial.hpp"
+#include "../../math/dynamic_mod_int.hpp"
 #include "../../template/template.hpp"
 
-#include <atcoder/modint>
-using namespace atcoder;
-
 int main() {
     int T, M;
     cin >> T >> M;
 
-    modint::set_mod(M);
-    Binomial<modint> bin(min(M - 1, 10000000));
+    DynamicModInt::set_mod(M);
+    Binomial<DynamicModInt> bin(min(M - 1, 10000000));
 
     while (T--) {
         int n, k;