Port modint

README.md

@@ -20,6 +20,7 @@ ac-library-python is a Python port of [AtCoder Library (ACL)](https://atcoder.jp
 #### Math
 
 + math
++ modint
 
 #### Graph
 
@@ -39,7 +40,6 @@ ac-library-python is a Python port of [AtCoder Library (ACL)](https://atcoder.jp
 #### Math
 
 + convolution
-+ modint
 
 ## Install
 

README_ja.md

@@ -18,6 +18,7 @@ ac-library-pythonは、[AtCoder Library (ACL)](https://atcoder.jp/posts/517)のP
 #### 数学
 
 + math
++ modint
 
 #### グラフ
 
@@ -37,7 +38,6 @@ ac-library-pythonは、[AtCoder Library (ACL)](https://atcoder.jp/posts/517)のP
 #### 数学
 
 + convolution
-+ modint
 
 ## インストール
 

atcoder/modint.py

@@ -0,0 +1,123 @@
+from __future__ import annotations
+import copy
+import typing
+
+import atcoder._math
+
+
+class ModContext:
+    context = []
+
+    def __init__(self, mod: int) -> None:
+        assert 1 <= mod
+
+        self.mod = mod
+
+    def __enter__(self) -> None:
+        self.context.append(self.mod)
+
+    def __exit__(self, exc_type: typing.Any, exc_value: typing.Any,
+                 traceback: typing.Any) -> None:
+        self.context.pop()
+
+    @classmethod
+    def get_mod(cls) -> int:
+        return cls.context[-1]
+
+
+class Modint:
+    def __init__(self, v: int = 0) -> None:
+        self._mod = ModContext.get_mod()
+        if v == 0:
+            self._v = 0
+        else:
+            self._v = v % self._mod
+
+    def val(self) -> int:
+        return self._v
+
+    def __iadd__(self, rhs: typing.Union[Modint, int]) -> Modint:
+        rhs = self._asmodint(rhs)
+        self._v += rhs._v
+        if self._v >= self._mod:
+            self._v -= self._mod
+        return self
+
+    def __isub__(self, rhs: typing.Union[Modint, int]) -> Modint:
+        rhs = self._asmodint(rhs)
+        self._v -= rhs._v
+        if self._v < 0:
+            self._v += self._mod
+        return self
+
+    def __imul__(self, rhs: typing.Union[Modint, int]) -> Modint:
+        rhs = self._asmodint(rhs)
+        self._v = self._v * rhs._v % self._mod
+        return self
+
+    def __ifloordiv__(self, rhs: typing.Union[Modint, int]) -> Modint:
+        rhs = self._asmodint(rhs)
+        self *= rhs.inv()
+        return self
+
+    def __pos__(self) -> Modint:
+        return self
+
+    def __neg__(self) -> Modint:
+        return Modint() - self
+
+    def __pow__(self, n: int) -> Modint:
+        assert 0 <= n
+
+        return Modint(pow(self._v, n, self._mod))
+
+    def inv(self) -> Modint:
+        eg = atcoder._math._inv_gcd(self._v, self._mod)
+
+        assert eg[0] == 1
+
+        return Modint(eg[1])
+
+    def __add__(self, rhs: typing.Union[Modint, int]) -> Modint:
+        rhs = self._asmodint(rhs)
+        result = copy.deepcopy(self)
+        result += rhs
+        return result
+
+    def __sub__(self, rhs: typing.Union[Modint, int]) -> Modint:
+        rhs = self._asmodint(rhs)
+        result = copy.deepcopy(self)
+        result -= rhs
+        return result
+
+    def __mul__(self, rhs: typing.Union[Modint, int]) -> Modint:
+        rhs = self._asmodint(rhs)
+        result = copy.deepcopy(self)
+        result *= rhs
+        return result
+
+    def __floordiv__(self, rhs: typing.Union[Modint, int]) -> Modint:
+        rhs = self._asmodint(rhs)
+        result = copy.deepcopy(self)
+        result //= rhs
+        return result
+
+    def __eq__(self, rhs: typing.Union[Modint, int]) -> bool:
+        rhs = self._asmodint(rhs)
+        return self._v == rhs._v
+
+    def __ne__(self, rhs: typing.Union[Modint, int]) -> bool:
+        rhs = self._asmodint(rhs)
+        return self._v != rhs._v
+
+    def _asmodint(self, rhs: typing.Union[Modint, int]) -> Modint:
+        if isinstance(rhs, Modint):
+            return rhs
+        else:
+            return Modint(rhs)
+
+
+def raw(v: int) -> Modint:
+    x = Modint()
+    x._v = v
+    return x