improve barret algorithm atcoder/ac-library#163

kzrnm · May 5, 2023 · 96b80b5 · 96b80b5
1 parent 960a0e8
commit 96b80b5
Showing 1 changed file with 2 additions and 3 deletions.
diff --git a/Source/ac-library-csharp/Math/Internal/Barrett.cs b/Source/ac-library-csharp/Math/Internal/Barrett.cs
@@ -26,9 +26,8 @@ public Barrett(uint m)
         public uint Reduce(ulong z)
         {
             var x = InternalMath.Mul128Bit(z, IM);
-            var v = unchecked((uint)(z - x * Mod));
-            if (Mod <= v) v += Mod;
-            return v;
+            var y = x * Mod;
+            return (uint)(z - y + (z < y ? Mod : 0));
         }
 
         /// <summary>