Add ModIntRuntime::facinv()

hitonanode · hitonanode · commit de121d62c69c · 2025-08-25T00:48:01.000+09:00
diff --git a/number/modint_runtime.hpp b/number/modint_runtime.hpp
@@ -117,6 +117,8 @@ struct ModIntRuntime {
         return facs()[n];
     }
 
+    static ModIntRuntime facinv(int n) { return ModIntRuntime::fac(n).inv(); }
+
     static ModIntRuntime doublefac(int n) {
         assert(n >= 0);
         if (n >= md) return ModIntRuntime(0);

Original file line number	Diff line number	Diff line change
`@@ -117,6 +117,8 @@ struct ModIntRuntime {`
`117`	`117`	`return facs()[n];`
`118`	`118`	`}`
`119`	`119`
	`120`	`+ static ModIntRuntime facinv(int n) { return ModIntRuntime::fac(n).inv(); }`
	`121`	`+`
`120`	`122`	`static ModIntRuntime doublefac(int n) {`
`121`	`123`	`assert(n >= 0);`
`122`	`124`	`if (n >= md) return ModIntRuntime(0);`